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

You can add an observer for NSNotification specifically JUST for your VC2.

// pasing the "VC2" here will tell the notification to only listen for notification from
// VC2 rather than every single other objects
[[NSNotitificationCenter defaultCenter] addObserver:self selector:@selector(doSomething:) object:VC2];

Now in in your VC2's view will disappear, you can post a notification:

-(void)viewWillDisappear
{
    [[NSNotificationCenter defaultCenter] postNotificationNamed:@"notif_dismissingVC2" object:nil];
}