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calvinc

macrumors member
Original poster
Jun 29, 2010
97
0
When I exit an app I just press the home screen button. Will it drain the battery a lot? Or do I need to close all apps fully?
 

Dominat0r

macrumors 6502a
Jul 25, 2009
716
12
almost anything running will eat battery....i close them most of the time within the multitasking window.
 

thecarrot

macrumors regular
Jul 20, 2010
117
29
I believe the way iOS4 works is that each time you press the home button to get out of an app it pauses that app where you left it (assuming it has been updated to do so) but does not actually keep it running. There are some exceptions which WILL keep running (GPS, pandora, etc) but most will just pause and you will not see a significant change in battery life
 

ethanehunt

macrumors newbie
Jun 21, 2010
11
0
It does drains ur battery

I noticed that it drains ur battery so fast...Initially I didn't know that, but when I saw my battery drained out so quickly, I realized it does drains ur battery
 

itsmemuffins

macrumors 68040
Jun 23, 2010
3,181
1,318
There are only three kinds of apps that you might want to close if battery is a concern.

GPS apps like Navigon.

Radio streaming like Pandora.

VoIP like Skype.
 

mattkowalski

macrumors regular
Jun 3, 2010
101
12
Pay more attention to the top-right of the screen (play icon, gps icon, etc), if you want to know what's running....
 

diabolic

macrumors 68000
Jun 13, 2007
1,572
1
Austin, Texas
When I exit an app I just press the home screen button. Will it drain the battery a lot? Or do I need to close all apps fully?

No, most apps you'll see in the recently used app list aren't using any battery at all. Unlike some other operating systems, iOS doesn't allow properly coded apps to stay running in the background and drain your battery. There are a very few specific tasks that run in the background, as mentioned in a previous post.

You don't need to free memory either. iOS does that automatically when it is needed.
 

0dev

macrumors 68040
Dec 22, 2009
3,947
24
127.0.0.1
The apps are not actually running, but they do use up RAM, so you should close them if you notice significant slow down.
 

tkao2025

macrumors regular
Jun 6, 2010
116
2
New York
I do notice that if you close the telephone, it takes longer to open up again. While if open in background it's instantaneous. Therefore I keep certain apps open because it's faster to open.
 

Mr Mot

macrumors member
Apr 26, 2010
76
0
Man, some of you guys are anal.

The phone app' is always running..if it wasn't, how would you receive calls?

The majorty of app's in the multitasking switcher aren't running, it's more a list of what you've used recently, in chronological order.

The only one to be weary of is Skype, that'll nail your battery and I think it's pretty obvious if an audio streaming app' is running.

GPS app's will eventually click onto the fact you're not coming back to them and GPS will be turned off.

If you want to only see what's running rather than a list of recently opened programs, you should jailbreak and install "remove recents."
 

Mark Booth

macrumors 68000
Jan 16, 2008
1,654
494
Some games continue to eat battery when they are paused in the background. The very popular game 'Angry Birds' is one of them! If I play that game in the morning and forget to go into the multitasking tray and "force quit" it, it easily wipes my battery that day!

Another app that eats battery when paused in the multitasking tray is 'SuperCam', an app I use to monitor video surveillance systems.

I'm sure there are other apps that you'd think are just "paused" but are really eating up battery!

Mark
 

geko29

macrumors 6502
Nov 10, 2008
291
2
If you want to only see what's running rather than a list of recently opened programs, you should jailbreak and install "remove recents."

Seconded. It does such a simple task, but "Remove Recents" is one of my favorite JB packages. Makes the task switcher so much cleaner and more useful.
 

samcraig

macrumors P6
Jun 22, 2009
16,779
41,982
USA
I don't care what Apple says or anyone else. I have seen battery drain "issues" when having some apps still in the task bar - oops I mean quick switch bar. Not anything major - but I would say 10 percent over the course of the day.

I clear it out whenever I finish using my phone at any given time when I know it will be idle for awhile.

Anal or not - don't really care. After a few weeks of testing, I've personally seen a difference.

Your mileage may and probably varies.
 

colmaclean

macrumors 68000
Jan 6, 2004
1,702
348
Berlin
I'd like to see the "quick switch bar" either:
* only contain apps which are actually running in the background.
* contain all apps, but highlight those which are running in the background.

The current model of just listing all apps you've previously opened is too vague.
 

diabolic

macrumors 68000
Jun 13, 2007
1,572
1
Austin, Texas
The very popular game 'Angry Birds' is one of them! If I play that game in the morning and forget to go into the multitasking tray and "force quit" it, it easily wipes my battery that day!

Do you have the latest version of Angry Birds? Since I never noticed it, as a test I started playing the game, then left the app in the middle of a level. My battery percentage hasn't changed at all in the past hour and a half.
 

err404

macrumors 68030
Mar 4, 2007
2,525
623
Both sides are right on this one. By and large apps in the tray use very little if any power and are merely consuming RAM. If that RAM is needed, iOS will automatically kill apps that have not need used in while. This could result in a slight delay for a new app to open as resources are freed, but it's not something you really need to concern yourself over. You'll spend more time manually closing apps than you would save opening them. Also keep in mind that the force kill is not a clean shutdown and does not allow the apps to save state. If the OS requests an app to shutdown, it has the opportunity to run a shutdown/save routine.
Unfortunately, things don't always work like this in practice. Outside of background Nav and Audio apps, iOS also supports Task completion allowing any app to continue running after exit. Typically it will wrap up it's work in a few seconds, but sometimes they will run for a while longer by design. For example some IM apps run for 10 mins or so after exit in order to continue receiving new messages before deferring to push notification.
And this were I feel the issues lay, bugs in the task completion code could result in apps never terminating. As iOS matures, I would expect these issues to subside. That said, most apps don't have a problem and I would recommend not bothering to manually kill your apps, unless you are experiencing battery drain problems.
 

Carniphage

macrumors 68000
Oct 29, 2006
1,880
1
Sheffield, England
And this were I feel the issues lay, bugs in the task completion code could result in apps never terminating.

I don't this statement is based in fact. When switching apps, most apps immediately save state there and then. If the system terminates them later, they don't need to be re-activated to perform a save.

Few make apps make use of the new task-completion feature. Those that do overstay their welcome are brutally terminated.

The whole point of Apple's multi-tasking mechanism is to avoid the need for the user to play nursemaid to ill-disciplined applications.

C.
 

Fliesen

macrumors 6502a
Mar 30, 2010
758
2
Austria
you only need to manually close apps if the save state is 'bugged' (which barely ever happens but might result in the app crashing over and over again when trying to open it)

mystical power draining is merely selective perception.
 

tekchic

macrumors 68020
Apr 19, 2010
2,056
1,763
Phoenix, AZ
I've started to close down everything I don't currently need. Comparing between mine and my husband's iPhone 4's, he could go an entire day and be at 80% (even after listening to 4+ hours of audiobooks). I could do almost nothing but a few check-ins here and there and check email and be at 60% in 5 hours.

The difference? I was checking into FourSquare, Gowalla, Yelp, Whrrl. No, the navigation icon wasn't being displayed in the bar at the top, so I assumed the programs were sleeping.

Once I started killing most check-in and news apps after exiting, I'm back up to reasonable battery life again. There definitely are some rogue apps that either have hella memory leaks or are calling home too often or something. I realize they're supposed to be "suspended", not calling home, etc... but the difference in battery life is too marked to not attribute it to that. To go from 60% after 5 hours to 90%+ after 5 hours is a huge difference -- and the only change is that I closed apps instead of letting them sit in the tray.

(Btw, I've always had push email set to hourly, even changed it to manually to see if that was it, and it still ate the same amount, so it wasn't email fetching).
 

err404

macrumors 68030
Mar 4, 2007
2,525
623
I don't this statement is based in fact. When switching apps, most apps immediately save state there and then. If the system terminates them later, they don't need to be re-activated to perform a save.
I agree that what you describe is the intended way for the OS to respond. Despite this, I was suggesting that bugs in either the OS or App could account for apps continuing to execute.
I wouldn't discount other user experiences just because they don't match yours. I have too many convincing accounts of abnormal power drain being "corrected" by killing apps for it to be entirely in peoples heads.

That said, killing apps should be considered a temporary work-around and should be periodically reviewed as apps and the OS are updated.
 

Corndog5595

macrumors 65816
Jul 16, 2010
1,112
0
This explanation is purely from personal experience and logical thinking. If I were to design multitasking, this is exactly how I would map it out on a device like an iPhone.

When you exit an app with ‘suspend-on-exit’ functionality, the app saves it’s state to the RAM and waits to be reopened. When you open it up, it will load automatically as if it was running on CPU and RAM the whole time.

If an app needs more memory than is available, or if there are too many ‘running,’ iOS will take a screenshot of a running app and then save their state to a folder (most likely the apps .app folder). When you open up the app again, it shows the screenshot (the current status bar is shown but everything else is the screenshot) while it loads the app up to the point it was at before. When it is done loading, the screenshot goes away and you are left with the interface that you left with.
 
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