All events that would trigger the applicationWillResignActive & applicationDidBecomeActive

I know pressing Command-L can trigger applicationWillResignActive: from forum here.

1) Is it only applied to IOS4?

2) Besides, in the real scenario with the device, what would trigger the applicationWillResignActive: & applicationDidBecomeActive:?

I searched answer开发者_C百科s in this forum. Some said it depends the reply of a call, some said sms, some said only an app which pops up a view. Is there a list of events I can find?

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applicationWillResignActive: is called before the phone goes to sleep, but it’s also called any time that your application loses the ability to respond to touch events.