ios How do I know the controller is a "push" or "pop" returned

Question

i have three controller and i wanna kown the controller is a push or pop

A controller:

{
    if(!b)
     b = [B alloc] init];
    [self.navigationController pushViewController:b animated:YES];
}

B controller:

- (void) viewDidAppear:(BOOL)animated 
{
     [super viewDidAppear:animated];
     //I want here to judge, from the "A" push over, or to return from the "C" "pop"

     //if it is push from A 
     //dosomething.....


     //if it is pop from C
     //dosomething
}
-(void)testAction:(id)sender
{
    C *c = [[C alloc] init];
    [self.navigationController pushViewController:b animated:YES];
    [c release];
}

C controller:

{
    [self.navigationController popViewControllerAnimated:YES];
}

thanks.

Answer 1

EDIT :

Add UINavigationControllerDelegate in .h file

Also do this:

[self.yournavController setDelegate:self];

Method below is navigation controller delegate which is called when the navigation controller shows a new top view controller via a push, pop or setting of the view controller stack.

Add this method

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{

}