iPhone: What is the correct way to leave an Application?

Question

Hallo Everyone,

with the iOS 4, the iPhone is supporting Multitasking, what is very nice, but something I do not wish to support in my Application. I mean, when the user press the Home-button, I want my application to finish and not to enter in Background. With the iOS 4, when the User press the Home-button, the App calls the applicationDidEnterBackground: delegate's method to enter in Background and in order to "force" the Application to finish when the user press the Home button, I've done following implementation:

- (void)applicationDidEnterBackground:(UIApplication *)application {
        //save everything...
    exit(0);
}

PROBLEM: I've noticed, that exit(0) brings the Application immediately to finish, without calling deallocating methods like "dealloc", and I think that is not a good programming style. So I would like to ask you guys, how to bring the application to finish in a "nicer" way.

Thanks in advance.

Answer 1

You are not allowed to. I know from experience: got an app rejection from Apple because I've exited (that was two and a half years ago but I doubt they've changed their policy here). There's a "private" (i.e. not mentioned in header file) method "terminate" on UIApplication, IIRC. But Apple says you may not do that. Only thing you can do is to show a dialog, asking the user to press the home button. But in turn doesn't work if on a device with multitasking enabled... so I guess you really have to change your application in such a way that you can throw away your state on applicationDidEnterBackground and start afresh on application on applicationDidBecomeActive.

Answer 2

That's two questions:

1. How to programmatically exit an iPhone app - duplicate

   http://stackoverflow.com/questions/355168/proper-way-to-exit-iphone-application

2. How to cause an iPhone app to not go to background in iOS4:

   Add the UIApplicationExitsOnSuspend key to your info.plist and set its value to YES http://developer.apple.com/iphone/library/documentation/General/Reference/InfoPlistKeyReference/Articles/iPhoneOSKeys.html#//apple_ref/doc/uid/TP40009252-SW23

Answer 3

What you actually want is not to exit the application (which is as mentioned not allowed), but tell the OS you would rather your application be killed rather than backgrounded.

There is an info.plist key for that, UIApplicationExitsOnSuspend. Set that in your info.plist to TRUE (checked) and then when your app enters the background it will be terminated.