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

isMovingTo/FromParentViewController won't work for pushing and popping into a navigation controller stack.

Here's a reliable way to do it (without using the delegate), but it's probably iOS 7+ only.

UIViewController *fromViewController = [[[self navigationController] transitionCoordinator] viewControllerForKey:UITransitionContextFromViewControllerKey];

if ([[self.navigationController viewControllers] containsObject:fromViewController])
{
    //we're being pushed onto the nav controller stack.  Make sure to fetch data.
} else {
    //Something is being popped and we are being revealed
}

In my case, using the delegate would mean having the view controllers' behavior be more tightly coupled with the delegate that owns the nav stack, and I wanted a more standalone solution. This works.