Add method to UINavigationBar back button?

Question

How can i add method to UINavigationbar back button, so whenever I click that back button I need to check some values and show UIAlertView? Is there any option for this?

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Answer 1

Suppose you have two controllers - Controller1 and Controller2. Controller2 is pushed from Controller1. So before pushing the Controller2 on the navigationController from Controller1

Controller2 *controller2 = [[[Controller2 alloc]  init]autorelease];
self.navigationItem.hidesBackButton = YES;   

Now, in the viewDidLoad: method of Controller2, add the following snippet

UIBarButtonItem *backBarButtonItem =[[[UIBarButtonItem alloc]initWithTitle:@"Back" style:UIBarButtonItemStyleBordered target:self action:@selector(goBackToAllPets:)]autorelease];
self.navigationItem.leftBarButtonItem = backBarButtonItem;

and in the backButtonClicked method, you can perform the checks you want to.