Public Service Announcement: You Should Not Force Quit Apps on iOS (daringfireball.net)

John Gruber, writing for DaringFireball: The single biggest misconception about iOS is that it's good digital hygiene to force quit apps that you aren't using. The idea is that apps in the background are locking up unnecessary RAM and consuming unnecessary CPU cycles, thus hurting performance and wasting battery life. That's not how iOS works. The iOS system is designed so that none of the above justifications for force quitting are true. Apps in the background are effectively "frozen", severely limiting what they can do in the background and freeing up the RAM they were using. iOS is really, really good at this. It is so good at this that unfreezing a frozen app takes up way less CPU (and energy) than relaunching an app that had been force quit. Not only does force quitting your apps not help, it actually hurts. Your battery life will be worse and it will take much longer to switch apps if you force quit apps in the background. [...] In fact, apps frozen in the background on iOS unfreeze so quickly that I think it actually helps perpetuate the myth that you should force quit them: if you're worried that background apps are draining your battery and you see how quickly they load from the background, it's a reasonable assumption to believe that they never stopped running. But they do. They really do get frozen, the RAM they were using really does get reclaimed by the system, and they really do unfreeze and come back to life that quickly.

Comments

Baloney

[Anonymous Coward]

Baloney. I have heard this argument so many times from OS developers. What does "effectively frozen" and "severely limited" mean? They are either frozen or they aren't. If they aren't frozen then they are taking up resources.

Re:Baloney

[jafiwam]

Or so they say

In practice, people who didn't know how to quit apps had shitty battery life... which stopped when they started closing apps.

Maybe newer iOS versions are better, however it has been very obvious through experimentation that closing apps helps performance.

Re:Baloney

[Quirkz]

5 or so years ago, it was definitely clear that leaving apps open was causing battery drain, and I obsessively closed everything as soon as I was done.

About a year ago I heard someone from Apple suggest it wasn't necessary any longer, and for the most part I leave things up and it seems to be true that they're not tremendous battery hogs.

Except Google Maps, of course. That burns through something like 1% of my battery every minute, and definitely keeps working even in the background. I will look stuff up, kill it, and repeat as necessary many times over rather than leaving it open any longer than I need to.

Re:Baloney

[aergern]

You can turn this behavior off in the settings so it will not continue running and using GPS when not in the foreground. So check the settings and be free! :D

Re:Baloney

[93 Escort Wagon]

I don't believe it's that cut and dried. I've had too many experiences where I get a warning, long after I stopped actively using a particular app, along the lines of "Waze still using your location in the background - do you want to let it continue?"

I expect that Gruber's description accurately depicts how it is supposed to work - and how it does work most of the time. And perhaps there indeed are people who "force quit" iOS apps on a regular basis for no good reason. But the few times I've seen someone do it, it's because they're trying to deal with some issue they think they're seeing right then and there.

Re:Baloney

[Jeremi]

Does anyone know why activating the iPhone's GPS receiver causes such a significant battery drain?

(In my naive imagining, it shouldn't take a lot of power to simply receive a GPS signal -- rendering an animated map could be expensive, of course, but Google Maps doesn't need to do that if it's running in the background)

Re:Baloney

[SirSlud]

As phones became more powerful, applications were using more battery. So people were all over the manual ways to preserve battery life. Software development on the relatively new phone OSes matured, and thus was able to move on to tackle "later" generation features like power-saving and efficiency (and the hardware became more efficient too, like the BT and GPS chipsets.)

Users usually lag behind stuff like this, and end up with habits of things they used to have to do long after the problem has been largely addressed in software optimization and feature work.

Re:Baloney

[MachineShedFred]

My girlfriend is one of those people that habitually closes everything on her phone. She then complains when the "smart lock" on my front door won't open for her, because the app that controls it is no longer running, and can't make a Bluetooth LE connection to the lock to verify the crypto key.

Don't know how many times I've told her not to close all the apps - it's unnecessary since about iOS 7 except for badly behaved apps, and things actually work better if you don't.

Re:Baloney

[InvalidsYnc]

At least a couple of years ago, an application that did not have any background refreshes running would effectively shut down and unload from memory after 5 seconds (that's why some apps take a bit longer to come up if you swap away from them for longer than that). It is supposed to release all resources (memory, storage, sockets, etc), I imagine that it only leaves a couple of pointers in place and then drags it all back in once you switch over to it again, but I have a hard time imagining how that is much more efficient than force quitting and launching it again.

Re:Baloney

[Incadenza]

Because you are not receiving 'a GPS signal'. You are receiving a multitude of GPS and GLONASS signals. From the time stamps and positional information encoded in these signals you then have to calculate your position. All these calculations are time-critical, so I guess they don't combine very well with power saving features.

Why there have beeen tremendous amounts in rendering speeds and all kinds of image processing, but not in the calculation of these GPS coordinates, that is a mystery to me as well.

Re:Baloney

[IcyWolfy]

Because:
1. it needs to power a separate radio to receive the GPS signals.
2. GPS sends out almanac data (rough position information) and ephemeris data (orbital information)
3. Your device needs to calculate the tragetory and position, and lock on to 4 satellites (3 for psotion, 1 for time) using this data
4. You device then needs to calcutate the total time-delta, to the nanosecond, between the time each satellite sends a message, and when you receive it.
5. ** Using this time delta, you can calculate your exact distance to each satellite.
6. Solve three overlapping sphere equations to triangulate your position at the ground.
7. Solve another equations using 4 satellites to calculate the equivalent atomic clock time.

Your device is processing dozens of messages per second, to keep the locks on each GPS satellite, to switch active satellites as you move out of view of any given satellite, and to keep your calculated position, and delta position (speed) all in sync.

It's very computationally expensive, and thus takes power to operate the chipset doing all this work.
In addition, if you're in a city, without clear line-of-sight to enough satellites, it can boost the power and try to make sense of fainter data, or try harder to calculate which satellites are in theory overhead, and then to obtain a lock on each satellite and it's orbital trajectory and speed. Net result: GPS uses more battery in cities than in countryside.

 

Re:Baloney

[SDLeary]

And then, of course, there is still the occasional runaway app, which is difficult to impossible to properly identify, save by a temp spike of the phone or tablet, necessitating at least quitting of all apps, or shutting down and restarting the system. SDLeary

Re: Baloney

[dougdonovan]

go ahead, turn your car off while doing 75.

Re:Baloney

[thegarbz]

Nothing to do with the iPhone. GPS receivers are active receivers that do a LOT of signal processing. The GPS signals were designed to beam through the atmosphere to fixed ground devices usually with very chunky or permanent supplies.

Power use didn't feature in the design conditions. A lot of modern EM design puts a lot of effort into the low-power portion of how to transmit, receive, encode and decode signals.

Re:Baloney

[tlhIngan]

Baloney. I have heard this argument so many times from OS developers. What does "effectively frozen" and "severely limited" mean? They are either frozen or they aren't. If they aren't frozen then they are taking up resources.

Apple has a few categories of apps that don't completely freeze up - e.g., apps that are VoIP related, audio related, location related. For these apps, iOS will let them run a background thread so they can continue to listen for calls (or handle the current call in progress), continue to play music, or continue to get GPS location information so they can update your position.

These apps don't freeze by default (though you can force iOS to freeze them even if they do this), since it's expected that you'd want your VoIP app / music player / map app to keep going even when it's not in the foreground. But just because they don't freeze completely doesn't mean the OS can't freeze the other threads that handle the UI, for example, and reclaim those resources.

And by severely limited, only those apps in thsoe categories can be backgrounded and still run. All other apps will be frozen.

Re:Baloney

[angel'o'sphere]

It is not the GPS signal, it is an App running wild and hanging in the background doing some nasty JavaScript shit.
The GPS chip is build in into the cellular network chip, so it is basically running all the time if you have a cellular network on your iPad/iPhone or its no true GPS but resting on WIFI/WLAN scanning.

Re:Baloney

[BasilBrush]

Early iPhones didn't run apps in the background AT ALL. SO they definately couldn't waste power. When Apple introduced background processing it was under very tight constraints. Very limited things they could do. Any attempt to just keep running resulted in the app being terminated by the OS after a few seconds.
A few cheated by keeping themselves open in the background supposedly streaming audio when they weren't. But Apple jumped on that pretty quickly.

There's never bee a problem with background apps eating up batteries on iOS. Some people don't understand what's going on, and swear they see improvements be quitting background apps. But it's just a placebo effect.

Re:Baloney

[beelsebob]

In the case of iOS it means that they're given 0 CPU cycles by the scheduler, and they're marked as available to be jetsamed from RAM on an LRU basis.

Re:Baloney

[Solandri]

IIRC (this was the explanation I got back when iOS couldn't multi-task), a non-multi-tasked app in iOS put into the background has its memory state saved, and the app is dumped from RAM just as if you'd closed it. When you "switch back" to the app, the app is actually restarted and the memory state restored. That is how Apple faked multi-tasking without actually multi-tasking. The app is "frozen" in that it can't do anything because it's actually removed from RAM (except for its memory state, which depending on the app could be smaller or bigger than the app).

Android's model is to keep background apps in RAM until it runs out of RAM. Then it (originally) starts sending a kill command to the app which hasn't been used in the longest time. I believe they've changed the kill sequence, as the original sequence encouraged apps to be battery hogs and needlessly do stuff in the background to keep themselves from being killed first. When an app receives the kill command, it's up to the app to clean itself up, save its state if needed, and shut down gracefully.

A user-commanded force close kills the app without giving it the chance to do all this cleanup, and can result in lost data or state. I would imagine the same is true for iOS.

Re:Baloney

[PIBM]

My old hand held gps could run over 60 hours tracking my position, recording it along with the precision, number of satellites used to receive it, and some other data to my SD card, sometime displaying the local map and my recent track, all while only using 2 1.5V 1600mAh batteries, using 12 years old technology. iPhones & android devices GPS positionning is much less precise than this old device, and use much more power. WTH.

Re:Baloney

[phantomfive]

It would be nice if the article had some benchmarks and graphs. The only benchmark the linked to (that I saw) was a benchmark for startup times between iOS and a Galaxy.

No data, no point.

Re:Baloney

[Carewolf]

It still is. It only makes no difference on the majority of apps, but a few apps are allowed to do things in the background and are very battery costly to not close. How are people supposed to know which apps are effectively frozen and which are hogs?

Re:Baloney

[Anonymous Coward]

If an app is "frozen" it gets no CPU cycles, it just takes up space in ram - and even that will be reclaimed as needed if ram is running low. With no CPU cycles, the biggest battery drain is eliminated (power for ram doesn't count because it's being used regardless of the ram's contents).

Other ways an app can drain battery include:
  - screen use (not if it's not in the foreground)
  - GPS (frozen apps don't get or process location updates)
  - network transfers (iOS prevents most background apps from doing network stuff, at least not without a very good reason)
  - wake lock (a broken app could insist the phone never enter sleep mode even while it's frozen in the background, but this is pretty rare)

Re:Baloney

[Darinbob]

The purpose to kill the apps may not be to save battery life, but to limit spying.

Re:Baloney

[Known Nutter]

* jettisoned

Re:Baloney

[beelsebob]

* jetsamed

It's a technical term on iOS meaning killed due to being in the background and there being a need for memory.

Re:Baloney

[ShanghaiBill]

Nothing to do with the iPhone.

Indeed. I have a Samsung Galaxy V, and it sucks power when the GPS is on. I only turn on GPS with I am actively using the map app.

Re:Baloney

[PCM2]

I don't know about iOS, but the Android phones I've used definitely don't have a GPS lock going all the time. In fact, I've seen it take a minute or two to get a lock, and even then it keeps chatting with the satellites to narrow down your location. That's got to be power hungry by itself, but in the meantime, Google Maps is undoubtedly using WiFi and cellular triangulation to get a preliminary result. All that network traffic is bound to burn some battery.

Re:Baloney

[heypete]

And yet, my u-Blox NEO-M8T module can receive GPS, GLONASS, and Galileo signals simultaneously, compute a fix, and provide a timing signal +/- 50ns, and still draws less than 67 mA as an absolute maximum. GPS ASICs use surprisingly little power.

Assuming the iPhone battery is 2000 mAh and isn't using other power (a poor assumption, but we'll go with it), the battery has enough energy to power such a GPS receiver for over a day.

Let's say someone uses their iPhone enough to drain the battery in 12 hours. That's an average current of 166 mA. With the GPS enabled and using 67 mA, that's a total of 233 mA: a 40% increase in the amount of power used, and would drain the battery in 8.6 hours.

I have no idea what GPS is used in the iPhone, and assume it's built into the CPU...but it really shouldn't use more power than the M8T. The fact that it does -- as do those in most (all?) Android phones -- surprises me.

Re:Baloney

[fnj]

Utter bullshit. A GlobalTop FGPMMOPA6H standalone complete GPS module (as used in, e.g., the Adafruit Ultimate GPS breakout) draws 25 mA at 3.3 v during acquisition, and 20 mA at 3.3 v while tracking. And it does all those same things you list. "Very computationally expensive", my ass. All the analog and digital stuff is run off a single tiny MediaTek chip MT3339, which includes a radio and an ARM7EJ-S core. The processor clock runs at no more than 98 MHz.

If you have a 2000 mAh battery, it ought to run the entire GPS load, minus display mapping, for 100 hours. You shouldn't be able to detect any effect at all in "minutes".

Re: Baloney

[F.Ultra]

But then they are also not frozen.

Re: Baloney

[F.Ultra]

Well technically it could have registered as a trigger event on the BT stack so it gets unfrozen when the BT stack sees data intended for the app. Of course it could then also start the app...

Re:Baloney

[jmauro]

The calculations aren't processor intensive, they're really quite easy. The battery drain is from the radio receivers, which are amped up to distinguish the really weak GPS signal from all the noise with the really small antennas built into the phone.

Re:Baloney

[jmauro]

My guess is that the hand-held GPS had a larger, more sensitive, frequency specific antenna than your phone does. As such it needs a much smaller (or even no amp) to receive the GPS radio signals.

Re:Baloney

[jmauro]

The iPhone has a BCM4774 chip to handle the GPS. It's a low power GPS chip.

There has been a specific GPS chip since the iPhone 3G.

Re:Baloney

[countach]

They ARE frozen, just with some exceptions. Like some download apps are allowed to stay awake for a limited time. Music apps are allowed to play (duh, or you couldn't listen) and some GPS apps are allowed to track you on their map. So for most apps, they are utterly frozen. But some classes of apps are not. But the advice in the main article is mostly right.

Re: Baloney

[fortfive]

>how are peole supposed to know which apps

settings>general>usage>battery

Re:Baloney

[superdave80]

There's never bee a problem with background apps eating up batteries on iOS.

Never say never.

My iPhone 4 showed terrible battery life a few weeks after I received it. I was having to charge it far more often then when I first had it. Then I discovered that EVERY SINGLE APP I EVER OPENED WAS STILL IN THE BACKGROUND! I had dozens of apps 'frozen', because I tired every app that came with the iPhone, and downloaded several more. Force quitting dozens of these apps solved the battery problem.

And lest you think that was some 'placebo effect', I also had an issue with some apps that I used at night before bed (exercise apps). Anytime I woke up in the morning to find my iPhone dead or near dead, inevitably I would see that I had forgotten to force close these specific apps. My guess is they were still holding onto the timer apps, since a timer was involved in these apps.

Some people don't understand what's going on, ...

Exactly.

Re:Baloney

[superdave80]

They aren't always frozen. I'm listening to my exercise timing app countdown right now on my iPhone 7, even though I am at the home screen and the app is in the background. So clearly some apps are still active even when you can't see them.

Re:Baloney

[superdave80]

except for badly behaved apps,

How do you tell all of the good apps from the bad apps? And doesn't your statement PROVE that background apps can use battery/resources?

Re:Baloney

[superdave80]

Yeah, I didn't get the whole 'startup' time argument, either. Nobody cares about that. We just don't want a bunch of 'frozen' apps we aren't using to suck up all of our battery. Which they can.

Re:Baloney

[superdave80]

That makes no sense. If there are ANY apps that can use up battery and resources when 'frozen', then the argument that you shouldn't ever force quit apps is bogus.

Re: Baloney

[Corbets]

One of the more informative posts I've seen on Slash in a while - I knew the basics but not the specifics. Thanks!

Re:Baloney

[serviscope_minor]

Why there have beeen tremendous amounts in rendering speeds and all kinds of image processing, but not in the calculation of these GPS coordinates, that is a mystery to me as well.

There has. Unlike with CPUs and GPUs many power saving options are not available. Things like power gating and clock throttling don't work because you are doing the same thing over and over again at the same speed for ever and ever. In terms of general improvement, the power has decreased except you've not seem much of that in phones because people want them to work in built up areas. The extra power budget has been spent on much more expensive multipath processing which can eat up almost arbitrary amounts of power if you do enough of it.

This is why phone GPS units are astoundingly much better than 10 years ago.

Re:Baloney

[hackertourist]

The iPhone uses AGPS, which tries to reduce reliance on GPS by triangulating a provisional position based on cell towers and Wifi base stations. This causes a large amount of cellular data traffic (the one time I tried this, 100 Mb/hour or 1 Mb/km). That may be the cause of the power drain.

Re:Baloney

[garote]

Wow. You have to switch it on and off manually to keep it from cratering your battery? What is this, 2008?

Re:Baloney

[garote]

You would be imagining incorrectly then.

iOS has not had to "fake" multi-tasking for quite a few versions now. Why base your imaginings on that?

iOS now selectively freezes applications on a per-thread basis, depending on the services identified as being handled by each thread, and orders the app to save state preparatory to being potentially killed shortly after is has been backgrounded in the UI. This effectively makes most apps flash-frozen in RAM, and all apps instantly killable on-demand if memory pressure demands it.

Going into the app switcher and "killing" them just wastes your time, and your device's battery, sending deallocation commands to things that are only there because the RAM hasn't been requested for anything else yet, or even worse, just loading the saved thumbnail images of the last seen state of an app that has ALREADY been deallocated (eating up some of your RAM as it does so) so you can flick your thumb upward on them and remove them from the list. There is honestly no point to this exercise except to indulge your OCD.

The real savings is in the designated threads for designated services: They are policed. A thread that is allowed to continue running in order to keep playing you music, for example, is actually disallowed from claiming more than a certain percentage of CPU time, and disallowed from accessing certain frameworks.

That said, some applications try to abuse this. A few versions and iOS updates back, there was a furor over the way Facebook behaved when it was backgrounded. It actually spun up a fake "music" thread, playing dead silence, and used it to fetch more network data than it was otherwise allowed, which in turn drained battery faster.

If you suspect there are apps doing nefarious crap like this, go to settings > general > usage > battery and look at the statistics. The culprit in your declining battery will be shown right there. If you want you can hit a few switches and deny that app all background activity.

Re:Baloney

[mjwx]

My old hand held gps could run over 60 hours tracking my position, recording it along with the precision, number of satellites used to receive it, and some other data to my SD card, sometime displaying the local map and my recent track, all while only using 2 1.5V 1600mAh batteries, using 12 years old technology. iPhones & android devices GPS positionning is much less precise than this old device, and use much more power. WTH.

Phones are a bit different as they're more like general purpose computers. I've yet to see a GPS device that functions as fast or smoothly as my phone... that didn't cost as much as my phone. Most cheap GPSs are plagued with bad resitive touch screens and incomplete data-sets that make findinf addresses painful.

In 2014, I has a Samsung Galaxy Nexus, with this phone I navigated from San Luis Obispo to San Francisco on a single charge, that was a 10 hour drive given various stopovers on Highway 1. I ended up doing this because I'd left my car charging kit back in Australia. The Nexus 5x I have now has over twice the battery life, not all phones have terrible battery life.

Re:Baloney

[MachineShedFred]

Yes, they use some resources. Nobody ever claimed they don't. The article claims that leaving them in the background uses less resources than force quit and re-launch. I don't know why that's hard to understand - it's exactly the same as putting a Windows PC into standby or hibernate instead of shutting down and rebooting.

And it's also demonstrably faster to use the app when it's "thawed" than relaunched - this is the assertion I'm making. Launching the lock app takes a good few seconds before it's available to respond to the bluetooth radio, at which point the lock stops trying in order to preserve it's own battery. In fact, when you force quit the app, you even get a notification on exit saying that you need to re-open it to resume access to locks. The app needs to be open / frozen in order to have hooks into the Bluetooth LE stack, so that when it sees the lock turn on it's radio, it can connect and exchange keys.

Re:Baloney

[necro81]

I think you are on the right track. I have a Garmin triathlon watch. It's the size of, ya know, a watch, and the battery is probably only a few hundred mAh in capacity. But it can track my location for more than 12 hours on a charge, while also communicating via ANT+ to various sensors and BLE to my phone.

Optimized RF circuitry and no-frills computation go a long way.

Re:Baloney

[Dr. Evil]

I leave location tracking on and run geofencing apps 24x7x365 and it doesn't make a dent in my battery life. The GPS has little if anything to do with Google Maps battery drain.

Re:Baloney

[tender-matser]

Because you are not receiving 'a GPS signal'. You are receiving a multitude of GPS and GLONASS signals. From the time stamps and positional information encoded in these signals you then have to calculate your position.

Those calculations couldn't be that expensive. Besides, they're probably mostly hardware accelerated.

With the cellular + wifi radios turned off ("aircraft mode") and the gps radio turned on (with a gps tracking app collecting all nmea data and gzip-compressing it into a file) AND occasional use of a mapping map (written with OpenLayers in javascript and pulling data from a local http server), my cheap chinese phone is able to hold a charge for ~2days.

I've never used an iPhone, but it's probably the google maps app which is doing something seriously fucked up (track and collect info about cellular towers and wifi hotspots and send it to google?).

Re:Baloney

[tender-matser]

In fact, I've seen it take a minute or two to get a lock, and even then it keeps chatting with the satellites to narrow down your location.

That was years ago. Most recent android phones take at most 10 sec to get a lock. It helps if the case is not made of metal.

It's not like the old Nokia N810, which needed half an hour to get a lock (and after two or three times wasn't able to get a lock at all, unless you flushed the corrupted almanach data file and killed the gps driver daemon).

Also, it doesn't "chat" with the satellites. The GPS radio on a phone is purely a receiver, like the FM module.

Re:Baloney

[superdave80]

The article claims that leaving them in the background uses less resources than force quit and re-launch...

My battery is a resource, and some of these background apps sure as hell use more resources 'frozen' than if I kill them. I don't know why that's hard to understand.

it's exactly the same as putting a Windows PC into standby or hibernate instead of shutting down and rebooting.

No, it isn't. When you hibernate a PC, the entire PC is stopped. When you 'freeze' an app, only that app is frozen. The iPhone is still running, and those 'frozen' apps can still use power and resources.

Re:Baloney

[tibit]

Please don't conflate location services with GPS. You can enable location services as a complete package deal, or you can turn them off. When they are enabled, the GPS radio is turned on, but on top of that all other enabled radios (cellular, WiFi, BT) are actively used to determine your position. The location service system then fuses the information from all of those sources, and from the "inertial" platform (magnetometer, gyro and accelerometer). So enabling location services can potentially ramp up power on several subsystems. That's not what some last-decade GPS receiver would do, and that's also why sometimes you can get decent location information indoors where there's no GPS reception of any kind. There's a department store that I frequent where there's no GPS signal (even very sensitive professional receivers stay unlocked) yet the phone is quite good at figuring out where on the floor you are. That's because it uses signal strength from wifi access points, fixed location bluetooth devices, a few iBeacons present on the floor, and fuses all that with inertial data.

Re:Baloney

[tibit]

Why do people keep forgetting that iOS location services uses GPS as just one of the possible inputs? When you have WiFi and BT enabled on an iPhone, enabling location services will increase load on those two radios, and on the cellular radio, and it will enable the GPS receiver, and it will also power up the inertial platform (gyro, accelerometer, magnetometer). The data is then fused from all of these sources. Generally speaking, the GPS receiver power demand itself is maybe 10% of the overall load burden caused by location services. And that's in line with what you're saying. Even in airplane mode you'll get load from GPS and inertial sensors.

Re:Baloney

[david_thornley]

I have an iPhone for convenience, so I can do things without having to research anything. If there's one app that drains my battery while not force-quit, it's easier for me to put everything on force-quit rather than figure out what I can and can't leave in the background. If there was one app, it's easier to leave it as it is rather than to change back and re-test.

Quitting doesn't seem to mess anything up. The iPhone is fast enough to bring back what I was doing in any case, and even if it drains the battery a touch to quit for good it seems to give me good enough life anyway.

Re:Baloney

[angel'o'sphere]

Thy have to be special programed for that.
And actually you are supposed to give them permission after installing, as far as I know.
A web browser or a ebook reader is frozen.

Re:Baloney

[angel'o'sphere]

iOS as far as I can tell has no GPS lock "all the time" either.
iOS devices have an icon in the title bar that shows when an app is accessing the GPS code.
Basically that only happens when an app like google maps or a local public transport app is in front and active.

Re:Baloney

[superdave80]

Thy have to be special programed for that.

If that is true, then their assertion that force closing apps is absolutely wrong, since there are SOME apps that will drain your battery.

And actually you are supposed to give them permission after installing, as far as I know.

What special permission are you talking about? I have background app refresh completely turned off for all apps. And when I go to the settings, the app can be given access to media/music, notifications, and cellular data. All of them are set to off.

A web browser or a ebook reader is frozen.

Then Apple can say, "Don't bother force closing web browsers and ebook readers." They need to stop peddling the fiction that ALL background apps don't use any resources.

Re:Baloney

[angel'o'sphere]

They need to stop peddling the fiction that ALL background apps don't use any resources.
No one at Apple said that.

Point of the article is that "some people think" that force quitting is a good thing. But that is in practice not really true.

Obviously it is a waste of time. Unless you are a developer and have an idea what apps are doing it is quite difficult to spot which app is using CPU.

Obviously if you have a map up in the background, that will use CPU and battery, more obvious is a music player ... however I have so many apps open on my iPad I can not count them. The battery life is basically only dependent on my screen brightness.

Ofc it uses more battery when I'm surfing a lot, and wifi is activated. You can save quite some power by deactivating the cellular mode and stick to wifi only, or do the opposite ... depending if you have accessible wifi or not.

On the other hand, it does not hurt you to kill apps you know you don't need.

Re:Baloney

[superdave80]

No one at Apple said that.

Except for Craig Federighi, Apple's senior VP of Software Engineering (https://www.macrumors.com/2016/03/10/force-quitting-apps-doesnt-help-battery/)

Point of the article is that "some people think" that force quitting is a good thing. But that is in practice not really true.

Force quitting apps that keep sucking up my battery is a very good thing. I've already given you an example above, and I have a few more that I've already mentioned in other posts.

Obviously if you have a map up in the background, that will use CPU and battery, ...

So, how do I get it to STOP using CPU and battery then? Force quit is the only way as far as I know. If there is another way, let me know.

The battery life is basically only dependent on my screen brightness.

My screen is completely off during the night when my background apps suck up all of my battery.

Re:Baloney

[Agripa]

The calculations aren't processor intensive, they're really quite easy. The battery drain is from the radio receivers, which are amped up to distinguish the really weak GPS signal from all the noise with the really small antennas built into the phone.

The first amplification stage is the only one which affects the signal to noise ratio and there is practically nothing to be gained by trying to use a lower noise figure to make up for the lack of antenna gain; the improvement available here is less than 2dB and probably more like 0.3dB with real parts. Increasing the gain after the first stage does not require significant power.

If there are excess power requirements for cell phone GPS receivers, then they are somewhere else. Their antenna performance is horrible leading to poor GPS performance no matter what is done.

Re:Baloney

[Agripa]

Because you are not receiving 'a GPS signal'. You are receiving a multitude of GPS and GLONASS signals. From the time stamps and positional information encoded in these signals you then have to calculate your position. All these calculations are time-critical, so I guess they don't combine very well with power saving features.

Why there have beeen tremendous amounts in rendering speeds and all kinds of image processing, but not in the calculation of these GPS coordinates, that is a mystery to me as well.

There *have* been massive improvements in GPS receivers do to increasing integration. The first commercial receivers used a single correlator and time multiplexed it to iteratively monitor each visible satellite. Some modern receivers still support operating this way to conserve power but it is detrimental to GPS performance.

Re:Baloney

[Agripa]

In fact, I've seen it take a minute or two to get a lock, and even then it keeps chatting with the satellites to narrow down your location.

That was years ago. Most recent android phones take at most 10 sec to get a lock. It helps if the case is not made of metal.

They should be considerably faster than that.

The difference is not in the GPS receiver but in the phone implementing AGPS. A GPS lock requires downloading the ephemeris from each GPS satellite which takes 18 to 36 seconds. A phone using AGPS downloads the ephemeris for each GPS satellite through the network so this delay can be skipped.

In the past a GPS receiver had to download the 12.5 minute long almanac producing considerable delay but modern receivers can do a massive parallel code search for the satellites without it and obviously an AGPS receiver does not care about it.

Re:Baloney

[angel'o'sphere]

Ah, interesting link.
Perhaps I underestimate the amount of Apps that do backroundwork (for what ever reason).
As I said, on my iPad I rarely quit an app, and don't see differences in battery, besides screen brightnes and activating flight mode when I read on iBook.

Re:Baloney

[hackertourist]

I can rule out map data. I made a point of buying a navigation app that comes with an offline map, and updating that map before I set off.
Also, the iPhone keeps track of data usage per application. My navigation app downloaded 10 kb during that trip (traffic data), the System->Time and Location category sits at 134 Mb (again, for a stretch of highway ~100 km long).

Re:Baloney

[superdave80]

As I said, on my iPad I rarely quit an app, and don't see differences in battery,

I could see that with an iPad. The batteries on that thing are huge. I go forever between charges on my ancient iPad.

Re:Baloney

[angel'o'sphere]

Mine is an iPad 2 ... I guess I bought it about 2012. When not stressed it still runs 10h on one charge.

Why do they care?

[Train0987]

If iOS is designed so well then why in the hell should it matter if a user force-q1uits everything only to re-open it later? This makes me suspicious that they don't want you turning off certain things.

Re:Why do they care?

[Anonymous Coward]

And if it's better to have apps open and frozen, why don't they just open and freeze every app at startup and just leave them frozen but not visible if you force quit them? Why have a non-frozen closed state at all?

Re:Why do they care?

[Captain Splendid]

I think what they're trying to say is that the process of starting an App uses more resources than letting it sit in the background for however long. Which might be true in the lab, but when you're away from a wall socket and down to 10% you'll do whatever you have to do to keep your phone going and worry about the rest later.

Re:Why do they care?

[TFlan91]

It's not saying they don't want you to. It is saying that the reason you are doing it, may not be as valid as you might expect.

Re:Why do they care?

[SirSlud]

Re-opening it takes more power than unpausing it from the background. Like, the difference between hibernating and rebooting your entire computer. Applications do a lot of work when they are booted from an initial state vs coming back from sleeping. I guess your argument is that they should be designed to boot from initial state as efficiently as possible. In general, that's going to be a goal of the developer, but it'll never be as efficient as coming back from a state when some of the work performed when starting the application is already done and cached somewhere.

This is not rocket science.

Re:Why do they care?

[Train0987]

Well then as the AC above you points out why don't they automatically open and freeze every single app on boot?

Re:Why do they care?

[Train0987]

The amount of resources "wasted" re-opening an app is trivial.

Re:Why do they care?

[SirSlud]

Because then you'd be using resources to open every single app, many of which you may not ever end up using, which would also be wasteful of battery power.

Re:Why do they care?

[SirSlud]

Why have a non-frozen closed state at all?

For apps you don't use. What's your insinuation here, that every app you have installed you use at least once during one powered on cycle of your phone?

Re:Why do they care?

[SirSlud]

Not really. But what's important is that you do whatever helps you *feel* good, because lord knows that users always know better. ;)

Re:Why do they care?

[93 Escort Wagon]

In my experience, iOS' "Low Power Mode" works extremely well in terms of extending a phone's remaining battery life. Of course, one of the things it does is stop the background execution of most apps.

Re:Why do they care?

[Anonymous Coward]

Force quit is there because sometimes you need to do it.

The OS is good, but it's not magic. It can't always tell if an app somebody else coded is in an inconsistent or errored state.

There's a lot of uninformed computer voodoo that users buy in to. One of them is that force quiting background apps is a good idea. If there's any real benefit it's in their head.

iOS is /really/ good at suspending apps. I've had apps keep their state /between iOS upgrades/ - Exited a game, and came back to it weeks later after a major iOS release. Picked up exactly where it left off.

Re:Why do they care?

[MachineShedFred]

Really? There are some apps that take a good 10 seconds or so to become useable. It's assumed that it's not just on a 10 second timer, but actually doing things - running something on the CPU, moving information across a network, SSD I/O, etc.

Unpausing doesn't do this for the most part, and is usually rather instant on modern hardware.

Re:Why do they care?

[93 Escort Wagon]

If iOS is SO good at managing memory & other resources such that an app in this 'frozen state' uses 0 resources why not just 'auto launch' ALL apps when the device is rebooted to put them in this state?

It's the difference between RAM and "disk" (SSD) storage... you almost certainly don't have enough RAM to have all your apps loaded into it at once.

Re:Why do they care?

[R3d M3rcury]

If you're killing apps to save battery life, you're probably right--it's not making much of a difference.

If you're killing apps because they insist that they need to know where you are--even when they are not the foreground app--then it's certainly making a difference.

Re:Why do they care?

[Anonymous Coward]

so when it runs out of ram how the fuck does it work out which one you dont need..

Re:Why do they care?

[BasilBrush]

Just set permissions. Every app that uses GPS has an entry in the system settings/privacy/location services list. The options are Always/While-using/Never.

There is no reason to quit apps in the backgroud.

Re:Why do they care?

[angel'o'sphere]

Because I boot my jone only once or twice a year and have about 200 Apps on it?
When I reboot it, chances are: I need it! And don't want to wait for 200 Apps to load.

Re:Why do they care?

[BasilBrush]

And don't forget to wear a tin-foil beanie whilst using it. Can't be too careful after all.

Re:Why do they care?

[alexgieg]

Virtual Memory is a 1960's invention.

Re:Why do they care?

[Your.Master]

There's something to be said for doing this when the user does have the spare storage space to handle it. If the storage space becomes needed, the OS can freely kill processes that never ran in the first place to recover storage.

Re:Why do they care?

[DigiShaman]

About a year or so ago, I started turning on Lower Power Mode and used it for about a month. I stopped getting notifications automatically, and my battery life was substantially extended throughout the day. Pulling up a browser or any other app performed the same. Ditto for checking new e-mail. For the remainder of the time till now, I still flip Lower Power Mode on by default after I take it off the charger. IMHO, 99.999% of iPhone users wouldn't notice the difference missing pushed notifications. In fact, many would be extremely happy to have extra battery run-time available :)

Re:Why do they care?

[Dog-Cow]

iOS has no swap. It memory maps static resources, such as the code and the DATA sections of an executable, but it doesn't swap read/write memory to storage. This is done both for performance (even with SSD, swap is expensive) and because there's a limited amount of storage available.

Re:Why do they care?

[Dog-Cow]

Huh?

Re:Why do they care?

[Dog-Cow]

Because, unlike you and the AC, the Apple engineers aren't drooling idiots who wear slip-on shoes because they can't learn to tie laces.

Re:Why do they care?

[Dog-Cow]

iOS does not swap RW memory to storage. If there is memory pressure, frozen apps are killed to reclaim their memory.

Re:Why do they care?

[Dog-Cow]

If you don't want apps to track you, set the permission once and never bother again. For navigation apps, I agree that force-quitting is the only sane option. I do that, too.

Re:Why do they care?

[93 Escort Wagon]

I'm with you - I wish there was a "leave it on all the time" switch.

Re:Why do they care?

[Paul Carver]

This is not true. On my iPhone the only options for Waze are Always and Never. I use Waze on rare occasions. I absolutely don't want it tracking my position all the time but if I set it to never then it doesn't work at all. There's no option for "while using".

Re:Why do they care?

[hispeedzintarwebz]

Good lord, you should see the r/apple thread on Reddit about this. Some people are absolutely *militant* about making sure *no one* does this.

Re:Why do they care?

[alexgieg]

I don't know iOS architecture, so I'll trust your description as accurate and thanks for the information. :-)

But my point in replying that to the AC wasn't to suggest iOS used swap, but that managing memory so as to keep things that need running, running, and things that didn't need running, stopped, isn't a novel concept, much less the impossible magic he seemed to imply it was. Sure, the way iOS does it isn't the same, but the basic idea of how an OS would manage such a thing is far from a mystery.

Re:Why do they care?

[Aqualung812]

There's no option for "while using".

IIRC, this is fixed in iOS 11. The OS will force apps to have the "while using" as an option for all apps.

Where's Task Manager for iOS?

[Jeremi]

I was going to press control-alt-delete to bring it up, but I couldn't figure out how to plug in a keyboard... ;)

Re:Where's Task Manager for iOS?

[93 Escort Wagon]

I was going to press control-alt-delete to bring it up, ...

It's an Apple product, so that should be command-alt-delete. :-P

Re:Where's Task Manager for iOS?

[angel'o'sphere]

Actually it is command+alt+ ESC.

Re:Where's Task Manager for iOS?

[Anonymous Coward]

Tsk, that's easy: just swipe left, press the home bottom, pinch the top left part of the screen, hold the power button while tapping the screen not once, not twice, but thrice, lick the screen, and tap out the lyrics to "bohemian rhapsody" in morse code. Done! It's all just so intuitive.

Re:Where's Task Manager for iOS?

[Zatchmort]

It's simple, just use the 3.5mm jack. ;)

Distinctly untrue, despite the hype

[kaka.mala.vachva]

I have an iphone 6s, and I see the location icon come on when I check the weather (using the native app), because it is set to reporting local weather. Mostly, it goes away in a bit - but I have seen the icon stay on many times even when I have moved away from the weather app. I have to manually kill the weather app to make the location tracking go away.

Re:Distinctly untrue, despite the hype

[mrun4982]

This is the number one reason I force quite an apps. A bunch of location-using apps I use must be force-quit in order for them to stop using my location.

Re:Distinctly untrue, despite the hype

[93 Escort Wagon]

This is the number one reason I force quite an apps. A bunch of location-using apps I use must be force-quit in order for them to stop using my location.

Go to Settings -> General -> Background App Refresh and disallow any applications which you don't want to let run in the background... which is probably most of them.

It's a bit irritating that, for most apps, running in the background is enabled by default. There are very few which really need to do that.

Oh, and you may need to occasionally do that again. I've seen all those toggles get re-enabled after certain updates.

Re:Distinctly untrue, despite the hype

[JaredOfEuropa]

Disclaimer: I develop iOS stuff for fun (and sometimes make some money doing it).
Sometimes an app doesn't seem to be suspended completely and parts of it keep running. A few years ago the Facebook app was notorious for this: if you didn't force-quit the app it would often suck the battery dry in a couple of hours. This would happen sometimes even with apps that were not designed to run in the background, i.e. track your location or keep an ear out for certain events. But those few cases aside, the guy is right: in almost all cases it makes no sense force-quitting an app; just going back to the home screen will make it suspend all activity. And over the years iOS has gotten a bit better at suspending apps.

App developers have to do very little to make this happen: threads are stopped automatically after a while, the app gets notified so that it can wrap up stuff and save the device state, free up memory if possible, and so on. And even if you don't free up that memory like a good little boy, the phone will do it for you... pretty much by force-quiting your app when needed. Not ideal, but as a developer you have the choice of either releasing memory or just let the app die when the phone needs it.

Re:Distinctly untrue, despite the hype

[radarskiy]

Turns out location sensing has nothing to do with RAM usage, so your comment is a non sequitur.

Re:Distinctly untrue, despite the hype

[nine-times]

Yeah, I agree. Apps in the background may be largely frozen most of the time, but they can still be doing some stuff. They might be using the GPS. They might be downloading stuff. In fact, there was a bit of a dust-up a year or two ago because Facebook had designed their app to constantly download what was basically an empty file. I don't know all the technical details, but by constantly downloading a file, it kept the app from really freezing in the background, which meant that the app was able to update more frequently that Apple designed iOS to allow. It was using a bunch of bandwidth and draining battery life until Apple told them to knock it off.

So it's definitely not always the case that things freeze in the background. I think there's an argument to be made that it's generally not worth closing your apps *unless you're having a problem*. However, it doesn't seem to be at all true that open background apps don't use resources.

Re: Distinctly untrue, despite the hype

[Pieroxy]

If your turn it off then apps can't get your location, even when they are in the foreground and you want them to access it. Your solution is the equivalent of healing a sprain by amputating the entire limb.

Just turn it off for the weather app then.

Re: Distinctly untrue, despite the hype

[JaredOfEuropa]

With the newer versions of iOS, the chances of an app misbehaving are a lot smaller. It's harder for the developer to screw up, and the permissions have become a bit more fine grained and are pretty specific about running in the background, e.g. the phone now asks "allow location services even when the app is running in the background". Apps can only run in the background for specific reasons, although in this case I'm not sure how good Apple's vetting process actually is...

Still, if you suspect an app is being naughty and is sucking the battery dry, the Settings screen has an overview of how much battery each app has consumed in the past days. It's accurate enough to spot the offenders.

The struggle for battler life is real.

[zenasprime]

Mr. Gruber must not actually own an iPhone.

Re:The struggle for battler life is real.

[BasilBrush]

Gruber has owned and I believe still owns, every generation of iPhone.

He just hasn't fallen for the placebo that you have. There really is no benefit to routinely killing background apps. It's pure ignorance of how iOS works.

Re:The struggle for battler life is real.

[Carewolf]

Gruber has owned and I believe still owns, every generation of iPhone.

He just hasn't fallen for the placebo that you have. There really is no benefit to routinely killing background apps. It's pure ignorance of how iOS works.

Unless it is a map app, or app playing music, or app recording........ So it is a placebo for most apps, but for an important handfull of apps it is really important that you close them or they will use a LOT of power (GPS is costlyin battery).

So... You have fallen for the emperors new clothes and never realized everybody else was right.

Re:The struggle for battler life is real.

[superdave80]

There really is no benefit to routinely killing background apps.

Well, unless I don't want my battery run down because I left the wrong app 'frozen' overnight. It happens to me, so don't waste your time telling me it doesn't.

Re:The struggle for battler life is real.

[BasilBrush]

People on placebos are convinced they work.

Re:The struggle for battler life is real.

[superdave80]

So, the battery meter on my iPhone is showing me the wrong number due to a placebo effect? Weird...

Whatever....

[__aaclcg7560]

I turned off background refresh on 90% of the apps that I use on my iPhone 6s to conserve bandwidth (2GB monthly cap) and battery life. Very few apps need real time updates. The rest can wait for updates until I'm ready to deal with them on my home wireless network.

Re:Whatever....

[93 Escort Wagon]

I think I've got a grand total of two apps which are enabled for background app refresh.

Re:Whatever....

[__aaclcg7560]

I'll bet you keep Grindr and the Chick-fil-A coupon app going, right?

Close but not cigar. Kindle and email.

yeah, tell that to my old ipad2

[xforce]

If I keep just a few apps open it becomes absolutelly unusable, even with Background App Refresh disabled.

Don't tell me what to do

[imidan]

I force quit apps on my iPad because over time the list of apps that are 'running' gets cluttered with things I don't often use. I leave apps alone that I use frequently. I don't really care if this costs me some CPU cycles some day when I want to re-launch the app I quit.

Re:Don't tell me what to do

[radarskiy]

The list is ordered based on how recently you have used the app. If you don't use an app much, then the apps you use more often move to the front of the list automatically.

Only LUDDITES force quit apps.

[Anonymous Coward]

Modern app appers only APP APP apps, NOT LUDDITE force quit!

Apps!

Youtube and Waze

[Anonymous Coward]

I don't know what it is about those two, but unless I force quit them, they'll suck my battery dry within half a day (for Waze) or 2 hours (for Youtube)

Re:Really?

[SirSlud]

The point was don't force quit apps to save battery life. If you want to force quit apps because you're paranoid, then go for it.

Might as well turn the phone off tho - how do you know force quitting apps actually stops it? How do you trust anything at all on your phone if you don't trust that an app does what the developer publishes that it does?

Performance lies

[Falos]

There might be a discussion for bootups eating battery, but if you want an app to have performance RAM (and everyone writes their "mobile" bloatstains to waste plenty) you'll need to close recent apps. Not older ones, since iOS will silently kill those sessions (the slot in Recent becomes a placebo) as it desires. Hope it wasn't anything important.

This only matters for limited cases, say a phone game. And probably affects you less if you're overpaying (either for a laughable contract or the $800 iSubscription) to always have the latest models.

Re:Performance lies

[radarskiy]

'if you want an app to have performance RAM (and everyone writes their "mobile" bloatstains to waste plenty) you'll need to close recent apps. Not older ones, since iOS will silently kill those sessions (the slot in Recent becomes a placebo) as it desires. '

If the foreground app needs more RAM, iOS will suspend more and more old apps anyway. The different is that if you do it manually you also kill the running state of the app so when you reopen it you have the restart the app from the beginning.

No worries about RAM and CPU

[hcs_$reboot]

I force-quit some apps that are simply bugged, and reopening is a workaround. Even that Weather app (Apple), needs sometimes to be closed and reopened (or it doesn't refresh the weather / location)

Asinine

[saberworks]

This is asinine. And it's made worse by the fact that when you do use the app-switcher to switch to an open-in-the-background app, it's actually showing you a screenshot of the app as it was sometime prior to it getting frozen. When I reactivate the calculator app (not from a force-click, but open in the background), it shows a screenshot of calculator and I start tapping the numbers, but then the app actually becomes active and many of my taps were missed. I'd like it better if it showed a loading screen or something that would indicate that the app isn't ready yet. These things really aren't as quick as they say they are.

Re:Asinine

[Anonymous Coward]

These things really aren't as quick as they say they are.

it's amazing how computers got 1000x faster in the last 20 years, yet GUI elements seem to have the same lag profile as a generation ago :-/

Re:Asinine

[tepples]

it's amazing how computers got 1000x faster in the last 20 years, yet GUI elements seem to have the same lag profile as a generation ago :-/

Twenty years ago, a handheld device was a Game Boy Pocket. Nowadays, people expect more out of a GUI:

Proportional (not monospace) fonts
Scalable fonts
Languages with larger character sets than US ASCII
Higher pixel densities and bit depths than ~96dpi 2bpp grayscale
Gradients as cues for what can be pressed
Slide and zoom animations to reinforce the relationships among different activities rather than reliance on cutting from one screen to the next

Force-quit helps me work better

[davidwr]

I usually use only 2-3 apps at time. I force-quit everything else and use app-switching to get between them.

It's just easier for me that way.

Oh, to reduce battery drain I just disable background-app capability.

Why can't the user have control?

[jma05]

I use an Android phone. Aside from some small, personal apps I wrote for myself a while ago, I am not really an app developer and don't have an in-depth understanding of the issues.

But my annoyance is this: there are apps that I only use once a month and others not even that. I definitely don't need them running in any form, even with the lightest footprint and some of them are consuming power. They keep coming back the instant I killed them. Why do the modern OS vendors assume they know best? I would like to have control over the execution policy, not the app developer. In Windows, I could remove entries from the startup, task scheduler etc. In Unix, I have full control. Why can't I do that in modern operating systems? Yes, I am aware there are startup editors in Android. I found them unreliable or inadequate.

I as the user, have much better context information on how my apps need to run. Sure, people can shoot themselves in the foot, but provide a means to restore defaults when custom configurations aren't working, but don't take away control altogether.

Every commercial app developer wants his app to be ready to go. In Windows that meant far too many developers would add their apps to system startup. With enough such entries, it made a large proportion of consumer machines to go sluggish by swapping and many systems were upgraded just because the users did not know how to clean up their startup items. Sure, the modern systems prevent all that, but that does not mean I should not have any control. The lesson here is that developers cannot be trusted to be respectful of shared system resources (and so the OS takes over more control), not that the users cannot be trusted. At least, let the apps be better controlled in developer mode. It took what 5 or 6 versions before Google started allowing users to rescind permissions? I want more permissions (and with better granularity) to rescind.

Well, that was my rant. If I missed any obvious solutions, enlighten me.

Re:Why can't the user have control?

[BasilBrush]

This is about iPhones, not Androids. They work completely differently as regards background apps.

Re:Why can't the user have control?

[bingoUV]

On Android, I've noticed that disabling an app from startup is not enough . It is safer to completely disable apps using :

1. chmod 000 from command line . I haven't tried this after ICS, so can't be sure if this is still feasible.
2. freeze using the paid version of Titanium backup.

Re:It's all good in theory, but...

[radarskiy]

And that misbehavior has nothing to do with the RAM usage. Th epost is about the claim that you need to manually kill apps to manage RAM usage.

Measure it

[ricky_charlet]

settings->battery. Scroll to bottom for a report of how much battery each app has used. View it as last 24 hours, or as last 7 days. and FYI, (for me) Apple Mail, when connected to a corporate exchange server, sucks battery in the background. 30% overnight iphone 6s IOS 10.3

Battery life is no problem

[istartedi]

I'll just hook my iPhone up to this power outlet at the gas stat--BOOM! MacGruber!

Anyone else use the Shopify POS App?

[Vegan Cyclist]

Another example to doubt this claim: if anyone uses the Shopify POS App, you probably see that as you do more transactions with the swiper, the app gets slower and slower...and if you close and restart the app, it works fine again. Maybe this is true with some Apps, but I don't think you can say with all Apps...

Re:Anyone else use the Shopify POS App?

[coinreturn]

Another example to doubt this claim: if anyone uses the Shopify POS App, you probably see that as you do more transactions with the swiper, the app gets slower and slower...and if you close and restart the app, it works fine again. Maybe this is true with some Apps, but I don't think you can say with all Apps...

That's due to crappy programming. They probably have a huge memory leak in their code. Killing the app reclaims the leaked memory. That's a whole other story. The article is about power savings, not crappy apps.

Bull.

[chaoskitty]

I call bullshit. Leave Slack - which has NO notifications enabled, nor any other features allowed, alive overnight and check battery usage the next day and explain how a "frozen" app can take that much electricity.

ALWAYS force-quit Slack and other energy-hungry apps when you're not using them.

This is true for EVERY modern OS

[The MAZZTer]

Sure, for older OS versions, you may have found a hack or trick that improved your experience. So you got used to using it. But guess what? Over the years the developers have been iteratively improving their products. And they are aware of the issue you had in the first place, and probably fixed it a long time ago. Plus you now have better hardware than you did, relaxing many of the limits you were running into before. Trust that the designers of operating systems aren't relying on you to go and do manual processes to improve your system performance, but made sure things ran optimally without needing such hacks. Such things may in fact be hurting performance. I am specifically talking about old tricks still in use, of course, like force closing apps. Newer tips are more likely to actually have been tested on the OS you're using (but still be wary).

Another example, Windows will use unused memory to cache programs and files. Because unused memory is wasted memory. Despite this, you can run "RAM Cleaners" that eat up all your memory and quickly free it, forcing windows to dump its cache, slowing down your PC likely immediately as apps try to use objects that have to be recached from disk. But at least the RAM is clean!

I personally grew up in the era of MS-DOS. When you deleted a file, it was gone. Then as Windows 9x came along they had this fancy Recycle Bin. I didn't need it before, why would I need it now? I would keep doing things the way I was doing it because I knew better. Just bypass the Recycle Bin every time or even turn it off entirely.

A few instances of data loss due to accidental deletions later, I realized perhaps the designers of Windows were smarter than me in at least some respects ,and forced myself to begin using the Recycle Bin. My experience with accidental deletions has much improved.

That's what they all say

[WaffleMonster]

The same basic advice has been peddled and widely ignored by end users who know better across all major mobile platforms. The reality is this is only true for apps don't take advantage of facilities to sidestep background execution restrictions.

Many app intentionally seek to run continuously in the background to enable persistent stalking and download ads as these activities yield profits for app vendors. It should go without saying facilities exist across all major platforms to accommodate.

https://developer.apple.com/li...

Re:That's what they all say

[coinreturn]

"End users who know better" are the "parents who have done their research about vaccines" in the mobile device world.

You win the Internet today. Unfortunately, you posted AC, so we can't send you your prize.

Absolute garbage advice

[superdave80]

Back when I got my first iPhone (4), started trying out all of the apps it came with, and downloading a few new ones. After about a week or two, I noticed that the battery wasn't lasting as long. This is when I discovered how to view all of the apps that were still... frozen?... in the background. There were dozens of these. I force quit them all, made sure to force quit when I was done with an app, and the battery life went back to normal.

A few years later, I started using some workout apps that time rests and breaks in my routine. I usually used these at night before bed. Over time, I noticed that if I ever left these apps open, the battery would be dead or near dead the next morning, even if the battery was full when I went to sleep.

Apple needs to stop tell us that those background apps don't need to be closed, because they sound like idiots every time they say it.

Use a mock location app set to your preferred loca

[HalAtWork]

Use a mock location app set to your preferred location, this is what I do on Android, works fine for me and no battery hassles.

Re:If I were the head of Microsoft...

[tepples]

Attempting to mirror every single RAM write to an SSD within 100 ms would wear out an SSD fairly quickly and dramatically slow down certain common computations. Watch any game for an Xbox console become a slideshow, for example.

Re:Really, Mr. Gruber?

[tepples]

With which apps have you noticed this? If you can narrow it down to one, have you tried turning off the app's background sync or location use permission in Settings?

More to the point.. Tracking..

[thesupraman]

The reason we keep being told 'dont force close you apps' is that if you do, they cannot continue to do 'their thing' quietly in the background.
Their thing is often reporting things back to their developers - your position, actions, etc, etc..

THAT is why every now and then they remind us how foolish we would be not to keep them running.

Re:More to the point.. Tracking..

[cellocgw]

The reason we keep being told 'dont force close you apps' is that if you do, they cannot continue to do 'their thing' quietly in the background.
Their thing is often reporting things back to their developers - your position, actions, etc, etc..

THAT is why every now and then they remind us how foolish we would be not to keep them running.

Methinks both you and your phone need an aluminum foil hat.

BULLSHIT

[Khyber]

The very second you load Apple Maps and put it in the background, the GPS is still sucking the fuck out of your battery life, navigating somewhere or not.

That alone proves Apple is full of shit and lying.

ALWAYS kill your maps application after you're done using it, or you're going to quickly find yourself with far less battery life than you thought you had.

If an app *may* be wasting resources --

[iMadeGhostzilla]

then I have to treat it like it will and will force quit it. Unless I have a way to know that the app is definitely for sure not actively using resources, which currently I don't.

Same in Windows 8

[jader3rd]

This is why one of the "big" features of Windows 8.1 was the ability to close the WinRT based apps. People are so accustomed to thinking that anything which they're not using is eating away at resources, that everyone requested the ability to close them.

SIGKILL

[MrKaos]

Three years ago, out of curiosity, my colleague and I had a look to see what iPhones were doing from the OS BSD perspective. One thing we found was that to maintain stability processes were sent a SIGKILL to terminate them. It seemed like a hack, however probably reasonable for CPU bound processes. That's why it is good.

The rules remain that if these processes are blocked on I/O the will be unkillable and consume resources until it is restarted.

Re:SIGKILL

[countach]

How is it a hack to kill processes with SIGKILL? That's the completely correct way to kill a process on UNIX.

Re:SIGKILL

[MrKaos]

How is it a hack to kill processes with SIGKILL? That's the completely correct way to kill a process on UNIX.

Did you even read what I wrote: It seemed like a hack, however probably reasonable for CPU bound processes. I said it for a specific reason because whilst reasonable, it is not the correct way.

The correct way is to use SIGTERM first to give the process a chance to clean up, flush i/o and exit so the process does not become a zombie. After that, if the process does not respond, you apply SIGKILL.

Additionally...

[xploraiswakco]

The heaviest power using item on your iOS device is... The SCREEN.

This means when you waste your time force quitting the apps you are in fact using up more battery power than leaving them alone. It also means that since the apps take longer to startup fresh, your screen is eating even more power while you wait for the apps to startup.

As for backgrounding, force quitting apps does NOT quit the background process (if there is one). They all rely on whatever hardware they need to work, and whether the app has the necessary permissions (location services, microphone, background refresh, etc).

And this is 8 years of iOS experience talking.

A) BS B)This is about privacy

[EmperorOfCanada]

I shut down apps because I don't trust that they aren't pulling crap in the background. For instance many apps don't give the option to not locate when in background and only give you the options to locate or not. Well, if this is a map app I am forced to allow the locate. But I don't want that little bastard reporting any crap when it is not front and center.

I hate that I have to use facebook messenger to communicate with certain people. I 100% do not trust that crap to run in the background and not pull some privacy raping stunt.

Then there is the BS factor. I suspect that some apps are totally quiet in the background. But other apps are most certainly doing crap. A simple example is my audiobook app is most definitely still doing stuff when I am on other apps; this is a good feature, but a clear and simple proof that an app can do stuff while "hidden". How many other apps are either doing something that I don't want; Or are just badly programmed and just wasting time and energy? If the answer is one or more, then I will continue to swipe up with great glee.

I have a strong suspicion that these useless turds of studies are being promoted by people who really really don't want us shutting down their apps.

A feature that I would love is that I could say without any app being able to stop me (SHUT THE BUGGER DOWN WHEN IN BACKGROUND) and by shut down I mean not a single bit of info goes in or out, and the app doesn't get a single CPU cycle.

Quite simply, why won't the vendors of phones give us the privacy control that I want. For instance, I would love to not only be able to block most apps from having any network access; but I would love to have a granular firewall. For instance my browser could go to sites, but can't go to google anything, for any reason.

You SHOULD Force Quit Apps on iOS

[n329619]

It is good practice for consistence.

If even a single app broke the frozen state or took resources from the iphone, the reason to not force quit apps is already null. Not to mention that older iOS version might not be able to do that at all.

In addition, most users who don't keep force quit apps maintain a FULL running app list of all of their apps. Unless the iOS can ensure none of them will affect the user iphone performance, it is not good practice to tell users not force quit apps.

If an application is quit it should be unloaded

[Damouze]

People should not have to resort to drastic measures like force quit. If an application is exited, it should be removed from RAM completely, not 'frozen' or forced to the background.

There is a simple, valid reason (and design principle), for this: security. I do not believe for a second that an application that is 'frozen' has to stay that way, and I can think of at least a dozen ways for an app that is 'frozen' to be activated in the background. And once it is running in the background, who knows what vulnerabilities it exposes to the outside environment?

It is a design principle that I see lacking in both Android and iOS.

It's just tradition

[Waccoon]

Sounds like what Classic MacOS used to do. Remember when closing a window never actually quit the application? No worries, the OS is smart enough to swap out to virtual memory or some baloney, which never worked well.

Apps in the background are effectively "frozen"

So, at what point does the OS decide to "freeze" an app? Managing the CPU and memory priority of background processes is one of the great, unsolvable problems of OS design. Apple can claim to be really, really good at doing this, but unless the user has some level of control (and every app developer isn't lying and full of crap), iOS can't really do anything better than any other OS.

That's a lot of extrapolation there.

[garote]

"Dozens of calculations per second" hasn't been considered computationally expensive for about _40_years_.

The iPhone 7 contains a motion coprocessor chip that performs these calculations and tens of thousands more every second, using a vanishingly small amount of power. Positional data from wifi networks, cell towers, GPS, GLONASS, the compass, and the inertial sensors inside the phone is combined when and where available automatically. What isn't needed is powered down.

Even if getting accurate GPS data is harder in cities, it is irrelevant, given that cities contain way more cell towers and way more wifi networks, and the iPhone knows its position from those automatically in the course of normal operation without even needing to query GPS. ... which it does anyway because the power involved is, again, miniscule. Seriously: If the phone can detect three cell towers - practically a given in any good-sized city - it knows where it is just by being a phone. Ten years ago cell towers didn't provide the necessary positional and timing information for this to be so. Now they almost always do.

Let's all have some more humility here. Knowing something about GPS does not make us experts in the design of the most bleeding-edge mass communications tool on the planet, and/or the networks that drive it.

So?

[garote]

So change the per-app setting and disallow the app from doing anything at all in the background.
Problem solved, without a bunch of OCD force-quit finger-flicking every couple of hours.

Simple.

[garote]

It "freezes" an app the instant you are no longer looking at it on your screen.
For the purposes of a phone, or even split-screen operation of an iPad, this is extremely effective. You are only ever looking at one app - two at most - with perhaps some framework-delivered supporting information on the periphery.
Just because you can't imagine solutions to CPU/memory management for the general case, does not mean there aren't (often obvious) improvements that can be implemented for various specific cases. A small screen where a user tends to do one thing at a time is a perfect example.

Simple solution

[Mr_Silver]

The fault here lies with Apple who could resolve this misconception by simply redesigning the switcher screen.

Right now it shows both running and frozen applications so users have no idea which is which and end up trying to kill them all.

Three possible solutions off the top of my head:

• Greyscale the frozen applications with an additional indicator to reinforce the fact they aren't running.
• Place the runnning apps in a seperate list to the ones that are frozen.
• Simply not show the frozen ones at all (assuming people don't use the switcher to actually switch apps)

There are probably others.

Re:Simple solution

[sabbede]

Oh, that's a great idea!! Flat-out perfect!!

Maybe even have a second switcher just for the frozen ones, as I bet that most people tap the icon instead of using the switcher anyhow.

Not totally true

[gabrygenoa]

Apps that use background hooks (music players, downloaders, runners, navigators...) will use some battery if not "quitted", and also other applications that opt in for background usage IF you have 'background app refresh' setting enabled (and most not advanced users have it since it's enabled by default...).

RAM isn't the only memory to be concerned about...

[Kazoo the Clown]

What about the "disk" space it takes to maintain the frozen state of the app? Does force quitting an app free that up? RAM is only one kind of memory on the device, and not the only one that may be in short supply...

Not everything handles "freezing" gracefully.

[sabbede]

Video streaming apps tend not to wake up well in my experience, needing a force-quit/reopen cycle to reestablish their connection. Worse, they can interfere with what's running in the foreground. I've had to force-quit supposedly frozen streaming apps in order to get a browser to work many times. Most times really.

Plus, screw Apple for making me say 'apps'. I feel like an asshole every time I do. Popularizing that term might be the worst thing they ever did.

App management UI is too 'fun'

[ryanvanderzanden]

I think the app management, specifically the act of killing off background apps, is just too enjoyable of a thing to do (swipe up to send bits to the nevermore).

The biggest problem my crazy brain finds with background apps is when I am looking to navigate between them. Every historically launched app is there 'in the way' such that I feel compelled to kill off everything but my most consistently used apps (mail, podcasts, browser, etc) so they're easily accessible.

I know that the suggested route here is to put these apps on my home screen (which I do), but I'm somewhat obsessive about keeping things clean there, and find it oddly more time consuming to close the app, hunt and peck through rows of icons than it is to double-tap, so I tend to rely on the app switching UI.

Feels like iOS should know enough to know which are my top used apps and to keep those 'in front' of the lesser used ones, in which case I may not feel so inclined to force quit everything to keep it 'clean'.

Or, split the app switching UI from the "this is where I go to kill apps in a fun and satisfying way" UI. :)

GPS?

[idji]

What about apps that have permission "Access location always" instead of "access location only when active". I would like to think that force quitting them will stop it pinging.
I also have apps that download large files in the the background (e.g. podcast) and sometimes I want to prevent that.

What about Android?

[martinfb]

Does anyone know how Android fares on this topic?

I find that my Android smartphone gets regular Google crap popups - which are very annoying.
And I cannot determine the best way to disable this crap!

Same as Android

[GuB-42]

I don't know about how it works in iOS but Android has hundreds of useless task killer apps.
Apps are designed to listen to events and are restarted automatically when needed, and when the OS can kill tasks when it runs out of RAM anyways.

The only effective task killers are those that really freeze apps (ex : greenify), at the expense of disabling every background features like notifications.

Killing apps may still be effective for buggy apps stuck in a busy loop.