Checking if a UIViewController is about to get Popped from a navigation stack?

Question

I need to know when my view controller is about to get popped from a nav stack so I can perform an action.

I can't use -viewWillDisappear, because that gets called when the view controller is moved off screen for ANY reason (like a new view controller being pushed on top).

I specifically need to know when the controller is about to be popped itself.

Any ideas would be awesome, thanks in advance.

Answer 1

Override the viewWillDisappear method in the presented VC, then check the isMovingFromParentViewController flag within the override and do specific logic. In my case I'm hiding the navigation controllers toolbar. Still requires that your presented VC understand that it was pushed though so not perfect.

Answer 2

Fortunately, by the time the viewWillDisappear method is called, the viewController has already been removed from the stack, so we know the viewController is popping because it's no longer in the self.navigationController.viewControllers

Swift 4

override func viewWillDisappear(_ animated: Bool) {     super.viewWillDisappear(animated)      if let nav = self.navigationController {         let isPopping = !nav.viewControllers.contains(self)         if isPopping {             // popping off nav         } else {             // on nav, not popping off (pushing past, being presented over, etc.)         }     } else {         // not on nav at all     } } 

Original Code

- (void)viewWillDisappear:(BOOL)animated {     [super viewWillDisappear:animated];     if ((self.navigationController) &&          (![self.navigationController.viewControllers containsObject:self])) {         NSLog(@"I've been popped!");     } }