iOS how to detect programmatically when top view controller is popped?

Question

Suppose I have a nav controller stack with 2 view controllers: VC2 is on top and VC1 is underneath. Is there code I can include in VC1 that will detect that VC2 has just be

Answer 1

swift 3

override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        if self.isMovingToParentViewController {
            print("View is moving to ParentViewControll")
        }
}