Detect if back button is pressed AND wait user action to pop to previous view

Question

I saw multiple questions about how to detect when the user is pressing the "Back" button on a UINavigationBar, but the answers does not solved my problem.

Indeed, I want to display a UIAlertView when user is pressing the UINavigationBar "Back" button, to ask him "Do you want to save the changes ?".

I can display a UIAlertView when the user is pressing the "Back" button (with the following snippet), but the previous view is popped in the same time. And I don't want this behaviour ! I just want that the app WAIT the user answer BEFORE pop the previous view...

-(void) viewWillDisappear:(BOOL)animated
{
    if ([self isMovingFromParentViewController])
    {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Avertissement" message:@"Voulez-vous enregistrer les modifications effectuées ?" delegate:self cancelButtonTitle:@"Retour" otherButtonTitles:@"Oui", @"Non", nil];
        [alert show];
    }
    [super viewWillDisappear:animated];
}

Thanks for you help...

Answer 1

I Suggest you using you own LeftbarButtonItem instead of default Back-button event at viewWillDisappear like this:-

- (void)viewDidLoad
{
  UIBarButtonItem *left=[[UIBarButtonItem alloc]initWithTitle:@"Back" style:UIBarButtonItemStyleBordered target:self action:@selector(actionBack:)];
    self.navigationItem.leftBarButtonItem = left;
 [super viewDidLoad];
}

- (IBAction)actionBack:(id)sender {
   UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Avertissement" message:@"Voulez-vous enregistrer les modifications effectuées ?" delegate:self cancelButtonTitle:@"Retour" otherButtonTitles:@"Oui", @"Non", nil];
    [alert show];
}

And use alert Delegate clickedButtonAtIndex

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex  
    {
        if(alertView.tag == 1)
        {
            // set your logic
        }
    }