A good explanation of iOS multitasking: http://speirs.org/blog/2012/1/2/misconc ... sking.html

And because he got a shed load of emails, he made a video showing how it happens:
http://speirs.org/blog/2012/1/6/ios-mul ... etail.html

Yep, but it is those that do run in the background which cause the problems, like Skype, which can drain the battery in a couple of hours or navigation software. Those do need killing on a regular basis, if you need the battery to keep going through the whole day.

hmm... Have you tested Skype when it's in the background. I'll have a look in instruments.


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I am here: http://maps.google.com/maps?ll=53.842557,-1.532729

I hadn't used Skype for ages, then the iOS 4.3 update somehow automatically started Skype. My battery drained in about 4 hours. This went on for a day or so, with the phone being practically unusable and pretty much chained to a power supply. I then noticed that Skype had been started. I killed it and it went back to about 36 - 48 hours between charges.

It would appear that Skype behaives correctly, i.e. shortly after being backgrounded it is suspended (remaining in memory but taking no CPU time). if you get a text message or a call, Skype comes out of suspension, uses some CPU time, then goes back until you go back to the app or more messages come through. I guess Skype might be using push notifications to the app, which triggers the app to go and check for new stuff?

I only ran the app for five minutes, but it only appeared to use CPU time to receive calls/messages.

There's one thing you're failing to take account of in your otherwise reasonable analysis. It is this : Dave's iPhone hates him.

And his iMac....