- (void)alertViewCancel:(UIAlertView *)alertView is not called

Question

I've got the problem that the UIAlertViewDelegate method - (void)alertViewCancel:(UIAlertView *)alertView is not called when I cancel a AlertView with it's cancel button.

Weird is that the delegate method - (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex works perfectly.

Does anyone have an idea?

Thanks in advance
Sean

- (void)alertViewCancel:(UIAlertView *)alertView
{   
    if(![self aBooleanMethod])
    {
        exit(0);
    }
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    //some code
}   

I call this when a button is clicked:

- (void)ImagePickDone
{
    UIAlertView *alertDone = [[UIAlertView alloc] 
                          initWithTitle:@"Done" 
                          message:@"Are u sure?"
                          delegate:self 
                          cancelButtonTitle:@"Cancel" 
                          otherButtonTitles: @"Yes", nil];
    [alertDone show];   
    [alertDone release];
}

Answer 1

The alertViewCancel is used for when the system dismisses your alert view, not when the user presses the "Cancel" button. Quote from apple docs:

Optionally, you can implement the alertViewCancel: method to take the appropriate action when the system cancels your alert view. If the delegate does not implement this method, the default behavior is to simulate the user clicking the cancel button and closing the view.

If you want to capture when the user presses the "Cancel" button you should use the clickedButtonAtIndex method and check that the index corresponds to the index for the cancel button. To obtain this index use:

index = alertDone.cancelButtonIndex;

Answer 2

You can handle the Cancel at the index 0 of this delegate:

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == 0){
      //cancel button clicked. Do something here.
    }
    else{
      //other button indexes clicked
    }
}   

Answer 3

This can be improved in two ways. First, it only handles the case that the user actually clicked a button. It doesn't handle the situation that [myAlert dismissWithClickedButtonIndex:] is called, or that the alert is dismissed in some other way. Second, button 0 is not necessarily the cancel button. In an alert with two buttons, the left one is at index 0, and the right one is at index 1. If you changed the titles so that the right button says "Cancel", then button 1 is logically the Cancel button. Instead of "willDismiss" you can implement "didDismiss" which will be called after the dialog has disappeared and not before.

- (void)alertView:(UIAlertView *)alertView willDismissWithButtonIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == alertView.cancelButtonIndex)
    {
      //cancel button clicked. Do something here.
    }
    else
    {
      //other button indexes clicked
    }
}