Question

How can I know whether app is terminated by user?

(Double-clicking Home button and press red minus ‘-‘ button)

I need sample or pseudo code…

Answer 1

Sometimes you do get the UIApplicationWillTerminateNotification (you can also implement the applicationWillTerminate: method in your app delegate), but it’s not guaranteed that you do get any notification at all in this case. So don’t rely on it.

You won’t receive the notification if your app is “suspended”, that is it is in background but not running. In the suspended case you simply get killed with the non-catchable SIGKILL. Same for when you get killed due to out-of-memory.

From the documentation for applicationWillTerminate: (emphasis mine):

For applications that do not support background execution or are linked against iOS 3.x or earlier, this method is always called when the user quits the application. For applications that support background execution, this method is generally not called when the user quits the application because the application simply moves to the background in that case. However, this method may be called in situations where the application is running in the background (not suspended) and the system needs to terminate it for some reason.