Is there any callback for swipe back gesture in iOS?

Question

Sometimes when user go back to the previous UIViewController, I want to do something.

If the user clicked the back button in UINavigationBar, I can capture the event.

But if they use the swipe back gesture to go back, I cannot respond to the change.

So is there any callback for swipe back gesture?

Currently I can only disable this kind of page in my app through

interactivePopGestureRecognizer.enabled = NO;

Answer 1

The easiest way is to hook into the one that's already built into UINavigationController by doing something like this:

override func viewDidLoad() {
  super.viewDidLoad()
  navigationController?.interactivePopGestureRecognizer?.addTarget(self, action: #selector(MyViewController.handleBackswipe))
}
    
@objc private func handleBackswipe() {
    navigationController?.interactivePopGestureRecognizer?.removeTarget(self, action: #selector(MyViewController.handleBackswipe))
    // insert your custom code here
}

The remember to call removeTarget(_:action:) in your selector, otherwise it'll spam your selector until the gesture ends.