UINavigationController and back button action

Question

I have an two controllers 1st is self and 2nd is maincontroller, where I\'m pushing maincontroller in stack

Answer 1

Create your own UIBarButtonItem and set it as the leftBarButtonItem in viewDidLoad method of mainController.

For example (here I used a system item but you can also create a different one, see class reference for details).

UIBarButtonItem *leftBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(showAlertView:)];
self.navigationItem.leftBarButtonItem = leftBarButtonItem;

// only if you don't use ARC
// [leftBarButtonItem release];

where

- (void)showAlertView:(id)sender
{
    // alert view here...
}

Answer 2

Best and Easiest way

Try putting this into the view controller where you want to detect the press:

-(void) viewWillDisappear:(BOOL)animated {
    if ([self.navigationController.viewControllers indexOfObject:self]==NSNotFound) {
       // back button was pressed.  We know this is true because self is no longer
       // in the navigation stack.  
    }
    [super viewWillDisappear:animated];
}

Answer 3

add a custom back button with an action and set your alert in that action method.You can add your custom back button from here: http://www.applausible.com/blog/?p=401

Answer 4

First hide the back button by using

self.navigationItem.hidesBackButton = YES;

and then create your own Custom Button:

UIBarButtonItem *backBtn =[[UIBarButtonItem alloc]initWithTitle:@"back" style:UIBarButtonItemStyleDone target:self action:@selector(popAlertAction:)];
self.navigationItem.leftBarButtonItem=backBtn;
[backBtn release];

and your selector is here:

- (void)popAlertAction:(UIBarButtonItem*)sender
{
    //Do ur stuff for pop up
}

Answer 5

Or you can use the UINavigationController's delegate methods. The method willShowViewController is called when the back button of your VC is pressed.

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

Answer 6

create a button and give the button action as follows.

[self alert];

and when the alert is displayed, after tapping over yes

[self.navigationController popViewController];

after this,

self.navigationController.LeftBarButton = myButton;

this may help