Function called on viewController close (when application exit)? - ios

Question

I am looking for a function which is called on a UIViewController when the application exits.
I tried it out with viewWillDisappear and with applicationWillTerminate but nothing works.
I want to save my settings from the UIViewController in this function.

Answer 1

Like #Jeff said, but
In Swift 3:
override func viewDidLoad () {
super.viewDidLoad()
NotificationCenter.default.addObserver(self, selector: #selector(suspending), name: NSNotification.Name.UIApplicationWillResignActive, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(suspending), name: NSNotification.Name.UIApplicationWillTerminate, object: nil)
}
func suspending () {
print("suspending...")
}
UIApplicationWillResignActive happens when the app is swapped out, while
UIApplicationWillTerminate is triggered when exiting, such as when the Home button is pressed.

Answer 2

You need to register for notifications to know when the appropriate calls are made as an app terminates.
NSNotificationCenter .defaultCenter() .addObserver(self, selector: Selector("callBack"), name: UIApplicationWillResignActiveNotification, object: nil)
NSNotificationCenter .defaultCenter() .addObserver(self, selector: Selector("callBack"), name: UIApplicationWillTerminateNotification, object: nil)
func callback() {
// Save your settings
}
Remember to remove the observers in viewWillDisappear:
override func viewWillDisappear(animated: Bool) {
super.viewWillDisappear(animated)
NSNotificationCenter .defaultCenter() .removeObserver(self)
}

Answer 3

you can call deinit inside the ViewController
deinit {
deleteUnsavedPhotoFromServer()
}

Answer 4

Swift 5.5
Use For App Enter Background
NotificationCenter.default.addObserver(self, selector: #selector(appResignActiveNotify), name: UIApplication.willResignActiveNotification, object: nil)
#objc func appResignActiveNotify() {
//called when App enter background
}
For App Terminate
NotificationCenter.default.addObserver(self, selector: #selector(appTerminateNotify), name: UIApplication.willTerminateNotification, object: nil)
#objc func appTerminateNotify() {
//called when Terminate
}