How to transition between view controllers

Question

I have placed code in my App Delegate such that I can transition from one view controller to another.

However when I press the button, the transition to my SecondViewController is not made. How should I go about doing this? any simple way to bring next view controller,(pushview controller)...

Here is my code:

SecondViewController *aSecondView = [[SecondViewController alloc] init];
[self setSecondViewController:aSecondView];
[aSecondView release];

[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:2.0];
[UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft 
                       forView:window
                         cache:YES];
[viewController.view removeFromSuperview];
[self.window addSubview:[secondViewController view]];
[UIView commitAnimations];

Answer 1

Well, since you're not using the built-in functions for presenting view controllers, you will have to call all of the view*Appear: functions:

• -viewWillAppear:
• -viewDidAppear:
• -viewWillDisappear:
• -viewDidDisappear:

I'm not sure if that will fix the problem, though. You may want to instead use presentModalViewController:animated: to push the new view. If it's not logically a subview of the current view, then have a root view push the first view, then when you want to transition, dismiss the first view and present the second from the (never seen) root view.

Answer 2

While you haven't posted more of your code so I can't be certain, there's a code smell coming from doing your controller transitions inside your app delegate. Since you describe a button that initiates the transition, my question is, why aren't you using a navigation controller and/or presenting your second view controller modally, inside the view controller that owns the button?

Modify your app delegate judiciously -- I mostly only use mine for doing one-time, global tasks, such as loading a Core Data store/sqlite database, etc.

Answer 3

[UIView setAnimationTransition:UIViewAnimationTransitionFlipFromLeft forView:window cache:YES];

does not work on a actual iPad ... any ideas why ?