objective c - applicationWillTerminate not getting called on force quit of iOS app

Question

Does anyone have any insights into when/under what conditions applicationWillTerminate is called in iOS 5/6?

I've got some logic i'd like to execute whenever the application terminates (not moves to the background), for example if the user navigates to the application bar at the bottom of the screen by double tapping the home button and force quits the app.

when i try to do this on a test device, applicationWillTerminate does not seem to get called. Is there a reason for this?

My plan B is to tie that logic to some persistent object like a singleton or a static that is automatically destroyed when the app quits.

Any suggestions?

thanks

Answer 1

Have you read the documentation for applicationWillTerminate:,

It says,

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.

There is a "maybe" mentioned there. Probably that answers your question. So it is not necessary that this will get called when you quit the app. Probably you might have to use UIApplicationExitsOnSuspend to disable multitasking and then it might get called while putting in background. But that again depends on your app requirement. If you cannot disable multitasking, you might have consider doing that in applicationDidEnterBackground method or so. I am not sure if there are any other delegate methods which will help in identifying the force quit.