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Fraser Speirs, “Misconceptions About iOS Multitasking”:

There is one iOS “tip” that I keep hearing and it is wrong. Worse,
I keep hearing it from supposedly authoritative sources. I have
even heard it from the lips of Apple “Geniuses” in stores.

Here is the advice – and remember it is wrong:

All those apps in the multitasking bar on your iOS device are
currently active and slowing it down, filling the device’s memory
or using up your battery. To maximise performance and battery
life, you should kill them all manually.

Wrong. Wrong. Wrong. Wrong. Wrong. Wrong. Wrong. There are caveats
to this but anyone dispensing the advice above is clearly
uninformed enough that they will certainly not be aware of these
subtleties.

Fraser provides a great layman’s explanation of why this is wrong. Bookmark his post, show it to anyone who claims otherwise.

Bottom line: the iOS multitasking bar is not like the command tab switcher on Mac or Windows. It is not a list of currently “running” applications. It is simply a list of your most recently used applications, whether they’re running in the background, suspended in memory, or completely inactive. Notice, for example, that if you turn an iOS device off and on, completely restarting the device, the multitasking tray still shows the same apps. It’s like your browser history.

Emptying this list of applications is simply needless, mindless, busywork. It was absolutely never intended to be used this way and anyone who does this is just wasting their time. The system suspends apps running in the background automatically. The system removes suspended apps from memory automatically, when needed. Manually zapping all apps from this list is a voodoo placebo. The whole point of iOS’s multitasking model is that you, the user, should not have to worry about managing which applications are running and which are not. If you were supposed to do that, apps would have a Quit command. They don’t. You just go home, and the system should take care of the rest.

The worst thing about this story is that the advice is repeatedly coming from the people working at the Genius Bar in Apple stores. There was a discussion about this on Twitter over the holidays and I received a bunch of comments from readers who’ve been given this same “advice” when they’ve taken their iPhones to the Genius Bar to diagnose some actual problem.

Like with any voodoo, there are die-hard believers. I’m quite certain that I am going to receive email from people who will swear up-and-down that emptying this list of used applications every hour or so keeps their iPhone running better than it would otherwise. Nonsense.

As Fraser mentions, yes, there are exceptional situations where an app with background privileges can get stuck, and you need to kill that app. The argument here is not that you should never have to kill any app using the multitasking switcher — the argument is that you don’t need to do it on a regular basis, and you’re not making anything “better” by clearing the list. Shame on the “geniuses” who are peddling this advice.

from Daring Fireball http://daringfireball.net/ http://daringfireball.net/2012/01/ios_multitasking