Call function on app termination in Swift

问题

How can I call a function that is within an SKScene class when my app is terminated by the user?

I need to modify a value and save it to NSUserDefauts when the app is terminated.

回答1:

You can register to receive a notification when your app is about to terminate. To do this, add an observer to the default notification center by

// Add this to didMoveToView in your SKScene subclass
NotificationCenter.default.addObserver(self, selector: #selector(saveData), name: NSNotification.Name.UIApplicationWillTerminate, object: nil)

Add the following method to your SKScene subclass. The method will be called before the app terminates. It must be "exposed" to Objective-C by adding @objc so the notifier can use #selector().

@objc func saveData(notification:NSNotification) {
    // Save your data here
    print("Saving data...")
}

回答2:

In Swift 3 and 4 you have something like that: in your viewDidLoad

NotificationCenter.default.addObserver(self, selector: #selector(toDoSomething), name: NSNotification.Name.UIApplicationWillTerminate, object: nil)

and than you have that method to be called

 func suspending () {
        print("toDoSomething...")
}

回答3:

There are a few methods in UIAppDelegate that will help you. Take a look at applicationWillTerminate(_:) and applicationWillResignActive(_:). From there you see what state your app is in and do perform the appropriate actions.

来源：https://stackoverflow.com/questions/27010431/call-function-on-app-termination-in-swift

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