There’s been some heated discussion in the blogosphere about the misconception of the iOS multitasking bar. Most iOS users are under the impression that apps can drain battery life and hog system resources when left in the multitasking bar, but a developer by the name of Fraser Speirs has attempted to clear the air.

You don’t need to manually manage the iOS multitasking bar because the apps you see after double tapping the Home button are not actually “running.” In fact, it’s better to think of the multitasking bar as something like a browser history, not a task manager.

In his blog post, Speirs comments on the fact that Apple Store Geniuses have helped spread misinformation about the iOS multitasking bar for a long time. I’ve personally been told by Geniuses that I should remove apps from my iPhone’s multitasking bar to free up system resources and conserve battery life. This advice couldn’t be farther from the truth. The multitasking bar is nothing more than a glorified reference tool for the user to switch between recently-opened apps.

The proof is that you can reboot your iPhone and still have all of your recently-opened apps in the multitasking bar. There have been jailbreak tweaks that attempt to only show you the apps that are truly running in the background, but the typical user should never have to worry about such a thing.

For the most part, you should never have to touch your multitasking bar. When you press the Home button and leave an app, that app is basically put to bed. 9 times out of 10, any closed app will not continue to sit in the background draining the life out of your iOS device. There are, however, a few exceptions.

It’s helpful to categorize the different ways that iOS handles its apps. Speirs has done that for us:

  • Not running – the app has been terminated or has not been launched.
  • Inactive – the app is in the foreground but not receiving events (for example, the user has locked the device with the app active)
  • Active – the normal state of “in use” for an app
  • Background – the app is no longer on-screen but is still executing code
  • Suspended – the app is still resident in memory but is not executing code

There’s really no point in making this more complicated than it has to be, so I’ll get to the point. According to Speirs, Inactive and Active aren’t part of this discussion at all. I’m guessing that this because an Active app is all but frozen when your lock your iOS device. Whatever the reason, moving on.

Technically, all apps get only 5 seconds in the Background state. This is when you exit an app with the Home button. iOS gives each app a very limited window to clean itself up before it’s moved to the Suspended state. From there, a Suspended app remains in the device’s onboard memory so that it can be quickly launched again (sort of like how Mac OS X Lion handles apps now). Contrary to popular belief, the Suspended state does not use your device’s system resources or battery life. If there are too many apps in the Suspended state, iOS is smart enough to purge unnecessary suspensions and move apps to the “Not running” state.

Where it gets tricky is when apps request special permissions to run in the Background state for 10 minutes instead of 5 seconds. Speirs uses Instacast as an example. Instacast can tell iOS that downloading podcasts is a “background task,” meaning that iOS gives Instacast an extra 10 minutes to finish its download in the background. Once that 10 minutes is up, the app is forced into the Suspended state.

There are certain apps, like Mail, that will continue to run in the background. Audio, GPS, VoIP, Newsstand, and accessory/peripheral apps will all run in the background until they complete their task. From personal experience, Mail can be one of the biggest iOS system hogs. The app is continually fetching new emails for you, and each call out requires battery and CPU cycles. Unfortunately, the only way to make sure that Mail is having a minimal impact on your battery is to kill the app altogether when you’re not using it i. You can set Mail to only fetch email sporadically (every few hours, etc.), but for most people that defeats the purpose of having an email client on a smartphone. You want your email as soon as possible.

An excellent, third-party example of such a circumstance is the early days of the Skype iOS app. When it was first introduced, Skype’s app would single-handedly drain battery life into oblivion. After many updates, Skype’s app is now smart enough to handle itself pretty well.

All apps that require constant background activity to function properly (Maps, for example) should be written well enough to know when to stop using your device’s resources. Once Instacast finishes playing a podcast in the background, it should move itself to the Suspended state. The only time you should ever have to actually kill an app in the multitasking bar is when an app is not behaving properly. And when that does happen it’s the app’s fault, not iOS’s.

Bottom line: If you try to manually manage your iOS multitasking bar, you’re wasting your time. If Apple Store employees try to tell you otherwise, kindly correct them.

  • This is probably the best explanation of iOS multitasking that I’ve seen. Nonetheless, AT&T customer service probably won’t listen to me if I try to explain this to them when I call saying that they over-charged me for data. They of course, “know it all.”

    • Anonymous

      O wow dude , I just tried to explain that to AT&T when them bastard gave me reasons to my throttle. Them bastards think they know everything

  • Excellent synopsis, and a must read; especially for those new to iOS.

  • Dan

    it’s still good to close all apps if you want to free up ram though

    • Anonymous

      From personal experience my ram free’s up when i closed the apps from multitasking bar.

      • Dan

        yeah exactly, that’s why I always close them even if it doesn’t supposedly use battery

      • I agree, i will look at my memory in SBSettings and then close all my apps in the app bar, go back and what do you know, more memory. Another thing i have noticed on my iPad is alot of those apps will be running under processes. So I am wondering how true this really is……

      • Anonymous

        Oh yeah………………thats another thing,…………………………….RAM IS ALSO THE LAST THING YOU NEED TO WORRY ABOUT……………

        iOS takes care of RAM for you you.FYI

        Closing apps in the switcher is still 100% comletely pointless………….regardless.

        Look it up…………..do some research on how RAM works in your phone.

      • ziig… if ios took care of it then my ram would hypothetically go back up to 355mb after opening and then exiting an app such as message or the music or contacts. but sadly…. it doesnt. it drops to 320 then to 287 then to 250 and remains there till i use sbsettings to close down apps and free up processes.

      • Ram uses power in the bit on and bit off state. If you had 900 mb free, or 10 mb free, it makes NO difference! When you launch an app, it will dump… Lets say it will dump the 50 mb, and use 100 mb.

        As long as it does t get to 0 mb free, your fine. If it gets to 0 mb free, it reboots with the apple logo, and its EXTREMELY rare, only on a jailbreak utility that happens to have a memory leak and is part of springboard.

      • Anonymous

        @will it keeps enough of the app in RAM to use fast app switching rather than having to reopen the app from scratch. When you open a RAM intensive app that needed more RAM than available, it would kill the rest of the app.

        Doing it manually actually kills your battery quicker as you’re using more clock cycles running the app close routine more often than necessary.

    • Anonymous

      Agreed! When I find that my browser tabs are getting reloaded as I switch between them, I know my kids played games on it. After deleting all apps the browser stops reloading tabs. Essentially, iOS is not smart enough free up ram by moving background / suspended apps to not running state when some app like a browser needs more ram, so they are forced to not cache the inactive tabs.

    • Anonymous

      It doesn’t matter because the OS automatically closes apps to free up the RAM.

  • Chaotic Buddhist

    Except, that you’re wrong. That bar, although is more like a browser history, DOES allow you to kill an app that might not be behaving.
    To dismiss this as something nobody should have to worry about is as damaging as telling them it’s the task manager.

    • Anonymous

      But we’re talking about people who close the apps thinking that it saves battery.

  • Kok Hean

    The apps take up RAM though.

  • Gio

    This is not true. The ram is cleaned up only after you close apps from the multitask bar, that means they are still taking phones resources, thus draining your battery.

    • only cpu usage drains battery, not ram being used. swipes may get laggy till iOS cleans up some ram but IT IS NOT USING BATTERY. stop spreading these lies please.

  • Chaotic is right. While the entire app is not running in the background, the information last accessed thru that app remains, almost like a cookie. I have proved this by switching to an app via the multitasking bar and my last search/information is still there, whereas if I open the app directly without using the multitask bar, the app starts fresh at its “home” or search screen, so it must be storing some information there. Also when Facebook or other apps “mess up”, I delete that app from the multitask bar and it starts fresh from the opening screen and not where I left off. You can even do this with Maps if it is bogging down. Works every time. So while it may not be running the entire app in the background, it is storing “cookies” or last used data there which, although probably minimal, must use some resources

    • Did you read the whole article? Read “Suspended” again

      • My apologies. Reading the article via the Facebook app apparently didn’t show me the entire article. After reading it in Safari, I see the aforementioned section. Having said that, I am still not convinced that apps appearing on the multitask bar do not use resources, per my personal experience…

    • Anonymous

      I too just delete from my multitasking bar to restart a messed up app, but If a app messes up I prefer to hold the power button until the “slide to power off” comes up, then hold the home button to force close the app , just to give it that extra jolt of act right. Btw , this isn’t the same as the force shutoff by holding the power and home button at the same time

  • I always kill running processes when I want to free up RAM,an innactive running process its not draining battery but it reserves some RAM.
    So, its always usefull to kill some processes.

    Yo siempre mato los procesos cuando quiero liberar RAM, un proceso inactivo no está gastando batería pero reserva un poco de RAM.

  • Apparently certain parts of the article didn’t stick with people. Yes, apps in the bar can use your RAM (as I mentioned), but they are in their Suspended state, meaning that iOS will forcibly redistribute memory and kill apps completely when it needs more memory. The user has no reason to try and mange this when the OS is smart enough to do it itself. The only exception is when a badly-written app is hogging resources, like early versions of Skype.

    • Anonymous

      I understand exactly what you’re saying here. However, I am not sure that I believe that the OS does a great job of knowing when exactly to “forcibly redistribute memory when it needs more memory.” When my phone becomes sluggish, often times I’ll kill 10-15 apps in the in the bar and my phone will run a lot less sluggishly. I’ve done it enough where I can say it’s not a placebo effect. So while the OS may be capable of redistributing memory when needed…I would say that may not always meet a particular users preferences in this area and it may still be beneficial for some to manage this manually (or at least be a debatable subject rather than a clear cut answer).

      Thanks for the good read though. It’s interesting.

    • Andrew Piper

      I have an iPhone 3GS and it only has about 125mb of RAM, at least that’s what SBSettings shows me on my status bar. Every app I open reduces that ram and when I get close to 30mb everything on my phone gets slower. The home buttong is slower the animations are slower, everything. If I open Infinity Blade with 30mb available it takes 3 times longer to load then when I have 100mb free, so please clarify if your post is better suited for iPhone 4S or 4 with more RAM.

    • Anonymous

      Alex: The iPhone will eventually kill applications to free up memory, but that takes dealing with a painfully slow iDevice in many ways. Try it out by opening many applications, and then have multiple browsers with lots of tabs open. You will see a SIGNIFICANT difference in the response to the actions that you instruct the device to do.

  • Great article, but fails to address a few things, maybe you could update:
    1) Suspended Apps require RAM, and RAM needs to be refreshed (unlike storage memory) which takes battery.

    2)iOS devices have a limited amount of RAM. What happens when a new application is opened? How does it prioritize which apps remain suspended or running?

    3)Make clearer that suspended = in RAM but not running. Closed = neither in RAM nor running. Active = in RAM running in foreground. Backgrounding = in RAM running in Background

    Please update article, correct me if I’m wrong

    • Definitely, and the lack of ram makes the system LAG… which in turn, makes you want to “manage” a few things.

    • Anonymous

      1) I’m not sure if using 10% of RAM or 100% of RAM necessarily takes more or less battery.

      2) I think the most recent and frequently used apps are prioritized.

  • Emre SÜMENGEN

    You are most definitely wrong about the multitasker IS and how people should use their phones…

    The task switcher is not only the equivalent of taskbar in windows, but it’s not the equivalent of a browser history either… It’s BOTH.

    And, although as minimum as it can be, “running” apps keep draining battery and resources (RAM, cpu cycles and data).

    Guess what, I might not want Skype to stay online, when I quit the app…

  • Anonymous

    This is the same thing I try to explain to a lot of people……………………..That closing apps in the switcher is basically pointless………………….Finally IDB has a post about it………………………………….Less explaining for me to so.lol

  • excelent explanation of how the IOS Multitasking bar works, its not true mutitasking but is the best you can have on a smartphone, cause it doesnt drain ur battery and also dowsnt lag your device.

    • Anonymous

      Well considering that you have to work a app one by one anyways, I’ll consider it true multitasking. I do download movies as I’m doing other things, so yea it’s true multitasking, just better implemented

  • Damian Walusz

    Backgorounder from cydia gives the multitaskig! Once you install backgrounder, the apps in the switcher will be running constatntly until you remove them manually.

  • hmm i totally understand .. what i dont get is how a blackberry does their ” back grounding & Notifications ” so well without all that battery drain for such a useless phone .. would be preety awesome if my iphone waz able to do that ..

  • I don’t see much difference with 0 (zero) apps or if I have 100s apps “running” in multitasking.

    Though, sometimes, you have to manually close an app if it’s playing up.

    Generally, I don’t close apps. They’re sitting there all the time… If you think your phone is running slower, it’s probably because some of them apps are perhaps still running. They will eventually… stop running as described above… and act like a “recent app”.

    It’s not a rocket science.

  • Anonymous

    “Suspended state does not use your device’s system resources or battery life” but you said immediately prior to that “a Suspended app remains in the device’s onboard memory” hmm as far as i’m concerned that means a system resource IS still being used. when I use Remove Background how come SBS indicates a significant reclamation of RAM, sometimes from 25Mb back upto 130+ when I empty my so-called suspended taskbar? im not convinced we should leave everything alone, besides i hate clutter and it bugs me knowing there’s a list of old tasks sitting there 🙂

  • Anonymous

    “Contrary to popular belief, the Suspended state does not use your device’s system resources or battery life.”
    But it does use up memory, and can cause the iDevice to slow down

    “Suspended state, iOS is smart enough to purge unnecessary suspensions and move apps to the “Not running” state.”
    Which means –> When the system is running low of memory, the process will be killed.

    “Bottom line: If you try to manually manage your iOS multitasking bar, you’re wasting your time.”
    Not necessarily… If someone IS using it as a process management tool, then that is not a time wasting situation, unless you are taking into account the start up time of applications which are not suspended any longer because they were terminated.

    And, @ZiiG – I disagree with you. Can you please clarify, because I am curious as to why it is pointless. Also, can you please point to any good explanations on the internals of iOS’s memory management?

  • Anonymous

    On a different note: some other ways to manage running processes (apps) includes: RunningList, Multifl0w, SBS’s process list, and modifications of the Switcher to only show running processes (many of them).

  • Anonymous

    So many lies, mistruths and misconceptions in these comments. So here’s

    The Computer Scientist’s Guide to this article, in layman’s terms.

    The facts:
    – Lag is caused by low RAM
    – Higher RAM usage does not mean less battery life
    – Higher CPU usage does mean less battery life.
    – The multitasking bar is very handy for kill apps that are non-responsive/bugged out.

    Ok, so when you first boot up the device, it is your history showing in the multitasking bar – the last apps you used before rebooting. When you open an app, it loads up into RAM, obviously depleting it.

    When you switch to another app, some of the used RAM is freed up, the smart task manager only leaves enough to enable “fast app switching”. Those of you who were around for iOS 3 -> iOS 4 will remember apps having to be updated to make use of this. If they didn’t, pressing home would close the app and you would have to sit through splash screens (the image logos at the start of the app) and any loading screen. Fast app switching means you don’t have to do this any more.

    When the device uses up so much RAM that the new app that is opening hasn’t got enough, Apple has coded an unknown selection process to remove the fast app switch components from RAM. This is probably based on length of time last used by the user/data time idle, possibly with app usage statistics too – if you load up app X a lot, and it’s a choice between X and Y, it might kill Y first.

    On older device with slower processors with less RAM, animations may feel laggy for longer as the code to close the open apps to free up enough RAM takes longer than newer devices.

    Having a high usage of RAM is not a bad thing, it does not effect the speed a process completes on the CPU nor the length of time the battery will last for. Killing apps unecessarily will decrease both of these. Killing an apps of course causes the ‘Available RAM value to increase’ but requires the app closure routine to be run on the CPU, then later the app startup routine to be run too, when in reality the app could have just stayed inside the fast app switch mode instead.

    It therefore makes sense that the device would try fill up its RAM as much as possible and leave it filled to such a level where it neither has to kill the task killer code too often, nor the full app start code of any app too often neither. This is exactly what the task manager has been coded to do, and why the user initiating an mass-app kill sees a huge increase in available RAM. However, having lots of available RAM does not provide any benefit, whilst the mass app kill has used up a lot of CPU cycles, and thus battery, and even more is about to be used while you reopen your common apps again from their completely closed state.

    I hope this helps clear any confusion.

  • Simon Reidy

    Awesome article, but I think the last line may have caused a bit of confusion:

    “Bottom line: If you try to manually manage your iOS multitasking bar, you’re wasting your time”

    As explained, there’s no harm in leaving the majority of apps in their suspended state, and at most times you actually should allow iOS to take care of multitasking for you. While things like SBSettings will show more ram (as closing apps from their suspended state does free a little ram) the point is: this is a waste of time in most cases, as iOS should (and mosly does) automatically free resources when required.

    Only if apps are playing up, or in rare states of being truly backgrounded (like downloading a song) will the app use minimal resources until the process is finished.

    However when you are jailbroken the above article isn’t always the case. Apple’s tight “true backgrounding” rules no longer need to be as strictly adhered to by devs, so there can be some tweaks (or a combination of background processes) that use more resources than usual. People that heavily theme their devices with something like Winterboard for example, will notice there can be significantly less ram available. Not usually a big problem either, but iOS can no longer manage its 512MB (or 256 on the 3GS) effectivly if there are a lot more background processes it has to mange than usual.

  • ALSO, i want to know how jailbreak tweaks are handled in terms of memory suspension when not in use or the device is locked? Also is a Mobile Substrate tweak for Safari (Example) terminated wheen the Safari app is terminated? And what happens if said app is “Suspended”?

    Back on topic though I wish a developer would write a multitasking tweak with features such as (Suspend white list for apps you want to keep running in the background indefinitely not just for 10 minutes max, Suspend black list for apps that you want to just be closed and not suspended, Application priority list.) Etc etc. Therre isnt one tweak that covers this section of iOS, just aan outdated unsupported Backgrounder tweak 🙁

  • Is this also true for iPad?

  • m9k

    Unfortunately this is one of those cases where theory and practice don’t agree. I have just deleted apps from three iDevices starting with the most sluggish one, an iPad 1 that was almost painful to use it was so slow. The performance difference after deleting apps from the multitasking bar was enormous. All aspects of interactivity are in my estimation 2-3x faster. And this is on an iPad that is rebooted once or twice a week mainly in an effort to improve performance, which never really worked.

    There is clearly more to the story than the simple theory. My guess would be memory management in iOS leaves more than a little to be desired.

    The same deletion operation on an iPhone 4S and a 5 had similar but not as dramatic an effect.

    • Todd Sligar

      I couldn’t agree more, suspended apps and the history, cookies DO use ram, and in my case that dramatically slows safari to the point I think I’m on a dial up line. In my opinion safari should purge this stuff before slowing down, or have controls so that the user can either purge everything or partial purge. This has become a real problem for me since my iPhone is my only access to the Internet. I was hoping to find a app that does this for me, but to no avail. Thank you all for confirming what I thought to be true all along, but no one I have talked with has had this problem. Very good topic and informative.

      PS I found a quick way to shut down suspended apps: double push the home button, suspended apps will show in the task bar, touch and hold one of the icons and a – sign will show in the corners of the icons, touch the – sign and the icon disappears, and some ram is opened up. Most of you probably know this but I thought I would try to contribute something. Thanks again all, Todd

    • smith288

      You’re wrong. This has been demonstrated using Apples instruments app when leaving apps, memory and CPU was released unless the app was a type of app that requested more time (15 sec or something in iOS6) or was a GPS app.

      Apple handles it quiet well.

  • Scott

    All this article really purports is that it’s not the iOS’s fault when a backgrounded app drains your resources, but in the last couple paragraphs admits fully that badly coded apps certainly have the possibility of draining your resources. So it’s not a waste of time to close them at all.