Question

I have such error: when I click navigationbar.backItemButton I’m showing UIAlertView with two buttons. When I press on any of them application terminates just with EXC_BAD_ACCESS. Method – (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex don’t called. How can I solve it? Thanx!

//h – file

@interface DetailsTableViewController : UITableViewController <UITextFieldDelegate, UIAlertViewDelegate>

//m – file

- (void)viewWillDisappear:(BOOL)animated
{
    //if changes unsaved - alert reask window
    if (isDirty)
    {
        UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Save changes?"  
                                                      message:@"Press YES if you want to save changes before exit, NO - other case."  
                                                     delegate: self  
                                                    cancelButtonTitle: @"NO"  
                                                    otherButtonTitles: @"YES", nil];   

        [message show];  

        [message autorelease];
    }   
}

    - (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    NSString *title = [alertView buttonTitleAtIndex: buttonIndex];  

    if([title isEqualToString: @"YES"])  
    {  
        [self saveBtnUserClick];    
    } 
}

Answer 1

I think the problem is that after you tapped back button your current controller is removed from navigation stack and deallocated, so when alert tries to call its delegate methods it calls them on deallocated object which results in EXC_BAD_ACCESS error. To workaround the problem I see 2 obvious options (although there may be better solutions):

1. Extra retain your controller somewhere (in previous controller may be), but you need to find way to release it when you’re done.
2. Create your custom button instead of standard “back” and just show alert when it tapped. Then in alert’s delegate method pop your current controller from navigation stack.