Question

I have situation where I need to make sure that user has completed certain steps before they move to another tab inside UITabBarController. So if the user is in middle of something and taps on another tab, I would like to show a UIAlertView saying “you must complete blah blah blah before you go to another tab.”

Is it possible to to check this condition and cancel moving to another view controller?

Answer 1

Sure you can. I suppose you have your tabbar controller in the AppDelegate class. If so, set the AppDelegate to be its delegate. Then implement the following method

- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController {
  // place all the checks here
  EditingViewController *editingController = //link to controller where editing is being made.
  if (editingController && editingController.isEditing) {
    //UIAlertView
    return NO;
  }
  return YES;
}