iPhone + save state of application in case of any interruption

I have developed a game 开发者_高级运维as iPhone application. Everything is completed and I am ready to upload it on App Store. I need to implement only one feature and that is, when any interruption occurs like a phone call / a sms / a notification, I want to save the current state of game so that whatever user chooses: either to handle that interruption or to cancel that interruption, the game should start again from the same stage. How might I do this?

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Handle the

- (void) applicationWillTerminate: (UIApplication *) application

message in your UIApplicationDelegate. See the docs.