Why iOS Multitasking Isn't Killing Your Battery

We've explained before that task killers rarely improve performance on Android phones, and the same is equally true of iOS devices. Blogger and education consultant Fraser Speirs offers a well-explained summary of why shrinking the number of apps on your multitasking bar won't help extend iPhone battery life: because it's a list of apps you've run recently, not apps that are running right now.

Speirs offers a detailed explanation that's worth reading, but the gist is this: the apps you see in the iOS taskbar when you double-tap the home key represent recently used apps, not actively running apps. Unless the app falls into one of a small number of categories where background activity is required (playing music or checking your location, for instance), it will usually stop running in the background altogether within five seconds. Apple itself notes that this means battery life isn't impacted much, but it's good to have the detailed explanation if a friend tries to convince you otherwise.

Misconceptions about iOS multitasking


Comments

    finally i can stop dismissing those icons..

    I had friends who had been complaining that their iphones have been becoming laggy. These aren't tech savy friends so they didnt even know that i0S multitasking even existed, but after I showed them how to "close" those apps, they saw an instant improvement. So maybe its not all too bad to do some housekeeping every now and then

      Theres two things at work that i can think of in that situation:
      If an app is still in RAM, and a new foreground app wants more, its going to take a little effort for iOS to clear out that program and give access to the current app. Its a kind of black box trying to figure out how much ram is actually in use on an iOS device, but i believe iOS doesn't drop things from RAM until its necessary to save processing time. There is also the placebo effect.

    Not actively doing anything, sure, but still chewing up valuable RAM and making your device run like crap.

    But the main reason it doesn't chew up any additional battery is that it's not multitasking at all; it's task pause/resume.

    They are definitely still eating resources. If you jailbreak your iDevice and install SBSettings you can see the current available RAM. Open a bunch of apps and check it, then close them out from the tray and check again. You'll notice quite a difference.

      It's not battery life though. How the device uses and allocates ram is a seperate issue - it doesn't have to use battery power for a program to sit in memory.

        Mostly true. Some apps do in face stay in a 'running' state rather than just be committed to RAM. TomTom is a big one, if you go back to your Springboard and leave it running your battery will still drain very quickly. It actually notifies you after a while and asks if you want to close it completely.

    Then how does one explain 10% battery drain per hour until apps in the tray have been removed.

    I started out on the don't bother it doesnt make any difference, until out of desperation i cleared it to try fix my battery drain issue.

    Some apps dont behave and still run in background. For instance i have on numerous occasions had Metroview (GPS navigation app) play sounds when it shouldn't be running (the navigation was terminated the previous night, app closed, location services stopped being in use, so it should not be running at all, next morning unlock phone "*BEEP* SPEED LIMIT 100" when im on the home screen).

    So don't tell me apps are not still running.

      He said "Unless the app falls into one of a small number of categories where background activity is required (playing music or checking your location"... Your GPS app falls into the "checking your location" category...

      Another type of app that will keep running some background tasks are VOIP apps, like Skype... There was 7 types of app tasks that could run in the background when I had the iOS4 SDK -- it may have increased in number since then...

        I was well aware of that, i thought i was clear but obviously not.

        With guidance terminated the GPS apps should not remain running in the BG, but sometimes they do.

        Since its virtually impossible to tell if its running (if apple were not so damn lazy/stupid they would differentiate so people could tell if it was still running) Even better would be a what apps are using what percentage of the battery/cpu/ram/network/location services like android does.

    I don't get it: "iOS multitasking isn't killing your battery life at all - except for those apps where it is?"

    Skype and TomTom will definitely kill your battery much faster than if they weren't on.

    Well I know for a fact that "Buzz Player" keeps on running even after you return to the Home Screen. There is no "close" or even an "exit" button in that app. So the only way to get out of it is to go to the home screen. I've not got an iPhone but rather an iPod Touch. Normally I can leave my iTouch in my bag for days (even a week or more is not unheard of) at a time on a single charge.. and it keeps the charge well.

    However, any time I forget to go into the multitasking bar and force close "Buzz Player", the battery is dead within less than a day. It's so dead that it shuts the iTouch off.

    So while it may be true that some apps stop running.. not all of them do and it's not just the Push Service ones, nor the GPS ones..

      I should add that I have stopped the playback completely and exited the video back to the video selection screen before exiting the app. So nothing is "playing" in the background.

      iTouch make finger print door locks not iPods
      http://www.itouchelectronics.com.au/

    As has been mentined previously, the big exception is navigation apps, or indeed any app that keeps your gpsr active.
    If you see that gps arrow at the top of your screen (between the time and battery indicator) you can be sure your battery is working harder than it needs to.
    Make a point of opening the app tray and killing any app that uses gps as soon as you are done.

    Article is lies.... Most apps on iOS run in the background if not closed in the multi-tasking tool bar these days. Facebook is one that you can clearly see runs in the background. When you open it from the home screen, if it was running in the background it will take you straight back to where you were and if you were writing a comment/status, that text remains. However, if you open facebook having closed it on the multi-tasking toolbar, it displays the facebook splash for a moment then takes you to the news feed.

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