Mobile devices usually have some kind of notification to tell the application that it is going to background, or it is going to be closed, battery low, etc...
I'm also interested on that. For example, a good game behaviour is not only pausing when going to background, but also show the "Pause Screen", so the user is not take on surprise when the game goes back active.
I believe these kind of events are pretty much the same on all mobile devices, with different implementations, of course.
Cheers
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Paulo
http://www.mobilecreators.com