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

What are you specifically trying to do?

If you're trying to detect that VC1 is about to be shown, this answer should help you. Use UINavigationControllerDelegate.

If you're trying to detect that VC2 is about to be hidden, I would just use the viewWillDisappear: of VC2.