Apple Executive Confirms: Manually Quitting Apps Doesn't Improve Battery Life (bgr.com)

An anonymous reader writes: Apple software engineering VP Craig Federighi recently dispelled one of the more long-standing myths about iPhone battery life. In short, if you spend a few minutes every day double clicking the iPhone home button and manually closing up applications in an effort to maintain battery life, you're wasting your time. The reality is that the applications you see upon opening up the multitasking pane are actually nothing more than static images intended to represent a list of your most recently used applications. Apple support documents have indicated, "generally, there's no need to force an app to close unless it's unresponsive." Apple support docs further explain: "After you switch to a different app, some apps run for a short period of time before they're set to a suspended state. Apps that are in a suspended state aren't actively in use, open, or taking up system resources."

Comments

Waze

[Chmarr]

Except Waze... Waze is a battery hog. I always quit that as soon as I'm done with its navigation features.

Re:Waze

[MightyMartian]

And Facebook, an app that just eats cycles and battery life on both iOS and Android. That such a major player as Facebook writes such a shitty awful resource hogging app frankly shocks me... until I remember iTunes on Windows.

Re:Waze

[LordKronos]

Exactly, and there's other apps too. I don't recall if it was in another slashdot discussion or somewhere else, but this topic came up recently and someone pointed to some sort of documentation or other official info on the matter. The gist of it was that apps only have a limited (short) amount of time to run in the background, and then they are forced to shut down. It then went on to say that certain apps that have permissions for certain things can continue to run.

So in summary, apps are not allowed to continue running in the background....unless they are allowed to do so. Which makes the entire argument of "you don't have to manually close them" complete bullshit. Maybe you don't need to for MOST apps, but there are still plenty that do have the permission to continue running.

Re:Waze

[pr0fessor]

This is one of those instances where they forget that there are some apps that actually do continue in the background and that they are really popular.

Re:Waze

[ShanghaiBill]

That such a major player as Facebook writes such a shitty awful resource hogging app frankly shocks me...

It should not shock you. Big companies write some of the worst apps. If a small company makes a crappy app, they are out of business. But a big company doesn't have much at stake. So they design by committee, and their coders and QA are not even on the same continent. I have an Amazon Echo, and their Alexa app is one of the worst I have ever seen. Every time it wakes up, it spends several minutes spinning the "pinwheel of death" ... just to display the shopping list. Then while I am getting the orange juice, it goes back to sleep, and I have to wait again before I can get the next item. It is so painful to use that I just open the list once and copy it onto a piece of paper.

Re:Waze

[EvilSS]

And Facebook, an app that just eats cycles and battery life on both iOS and Android. That such a major player as Facebook writes such a shitty awful resource hogging app frankly shocks me... until I remember iTunes on Windows.

Facebook was actually caught cheating once by playing inaudible audio to prevent iOS from putting it into sleep.

Re:Waze

[tlhIngan]

Exactly, and there's other apps too. I don't recall if it was in another slashdot discussion or somewhere else, but this topic came up recently and someone pointed to some sort of documentation or other official info on the matter. The gist of it was that apps only have a limited (short) amount of time to run in the background, and then they are forced to shut down. It then went on to say that certain apps that have permissions for certain things can continue to run.

So in summary, apps are not allowed to continue running in the background....unless they are allowed to do so. Which makes the entire argument of "you don't have to manually close them" complete bullshit. Maybe you don't need to for MOST apps, but there are still plenty that do have the permission to continue running.

Apps get around 5 minutes to finish off what they're doing. That's it.

The exceptions would be apps that need to be running in the background - e.g., audio players, navigation apps and VoIP apps.

Audio players are obvious - it would be quite annoying if you put your Spotify or Pandora or the music player or other thing in the background only to have the music stop. Navigation apps are similar - you need to be alerted when you get close. (Waze and other apps also have to keep the GPS active, so it's a double hit on the battery). And VoIP/IM apps need to be active to keep you signed in.

Those are the general classes of apps that can keep background processing. Some apps, like Facebook cheat - they open an audio stream and then play silence, keeping them alive because iOS thinks its a media player app.

Navigation apps can't cheat as they reveal GPS usage.

Re:Waze

[93 Escort Wagon]

Facebook was actually caught cheating once by playing inaudible audio to prevent iOS from putting it into sleep.

"Once" was just a few months ago. Their patch to fix this issue went out on October 22, 2015.

Re:Waze

[BarbaraHudson]

On Androd:

• System
• Data usage
• Turn off cellular data
• Scroll down to the evil app (facebook)
• Touch the app's icon
• Turn off background data

Now the app won't be running except when it's in the foreground. You won't chew through your cellular data plan, and you won't get an alert when somebody in Oz posts while you're asleep.

Cell data will still work for the app when it's in the foreground, so problem solved.

Not always true

[vampirbg]

This is for regular apps. Apps that have background mode enabled can run in background and can consume CPU cycles. They can even use GPS, WiFi, LTE etc. That consumes battery. Most of the running or GPS apps run just fine in background. Otherwise they'd just stop recording once the screen locks or, worse, keep the screen on at all times.

Re:I don't think this is 100% true

[radish]

Apps which are put to the background are allowed to run for a little while to let them finish up what they were doing (e.g. saving something). Then they're suspended - their state is written to disk and they're flushed from memory. The screenshot is saved so you can see it in the list, and if you reopen it the app will be restarted from the saved state.

Apps can register themselves as requiring to run full time in the background, examples are navigators, messaging apps, etc. These will not be suspended, and can eat the battery. If you add one of those flags to your app without actually having justification to do so, you'll be rejected from the app store.

Re:GPS is next

[dbIII]

Wifi on the other hand. I get more than three days run time on my slightly aged phone with wifi off and less than a day with it on.

Re:Deliberate Confusion

[BarbaraHudson]

Horsesh*t. Or rather, Stalman Foot-cheese.

Stalman was talking about software. You' can change your system image on your phone. You can even make one yourself if you want to. You can make your own apps that work the way you want. And for those who aren't so fanatical, they're free to stick with stock system images that come with that all-important support (even if it's less than 2 years in most cases - it's not like it stops working after support ends).

If everyone did it Stalman's way, small cheap and smart smartphones wouldn't exist. "Everything should be open" - well, no manufacturer is going to put the big bucks into r & d making a product that anyone else can just legally knock off. Thus there would be no economies of scale, and too many hardware and software incompatibilities.

Them's the facts. Or do you want to go back to the time of home-brew computers, and a slew of different architectures and operating systems with software only available on any one particular system in a hit or miss fashion? It was fun, but it was also a bit of a PITA.