Confirm back button on UINavigationController

Question

I am using the storyboard for my app which is using UINavigationController. I would like to add a confirmation dialog to the default back button so

Answer 1

Easy peasy. Just cover the button with a transparent UIControl and capture the touches.

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

#define COVER_HEIGHT    44
    //make this an iVar:  UIControl *backCover;
    if ( backCover == nil ) {
        CGRect cFrame = CGRectMake( 0, self.view.frame.origin.y-COVER_HEIGHT, 100, COVER_HEIGHT);
        backCover = [[UIControl alloc] initWithFrame:cFrame]; // cover the back button
        backCover.backgroundColor = [[UIColor orangeColor] colorWithAlphaComponent:0.2]; // transparent
        // use clearColor later
        [backCover addTarget:self action:@selector(backCoverAction:)
            forControlEvents:UIControlEventTouchDown];
        [self.view.window addSubview:backCover];
    }
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];

    [backCover removeFromSuperview]; // prevent coverage on another view
    backCover = nil;
}

- (void)backCoverAction:(UIControl *)sender
{
    // decide what to do -- maybe show a dialog.
    // to actually go "Back" do this:
    [self.navigationController popViewControllerAnimated:YES]; // "Back"
}

This scheme also works for tabBar buttons, but it's more complex to determine the location.