title: PresentModalViewController or addsubview?
body: <p>Hi I am writing an app in xcode 3.2.3. All I want to do is switch to another view but I am unsure of the best way to do this. I can do it either of these 2 ways...</p>
  
  <pre><code>PreferencesViewController *screen = [[PreferencesViewController alloc]initWithNibName:nil bundle:nil];
  
  screen.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
  
  [self presentModalViewController:screen animated:YES];
  
  [screen release];
  </code></pre>
  
  <p>or using...</p>
  
  <pre><code>PreferencesViewController *screen = [[PreferencesViewController alloc]initWithNibName:nil bundle:nil];
  
  [UIView beginAnimations:nil context:NULL];
  
  [UIView setAnimationDuration:1.0];
  
  [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.view cache:YES];
  
  [self.view addSubview:screen.view]; 
  
  [UIView commitAnimations];
  </code></pre>
  
  <p>I have some problems with both of these methods. If I use presentModalViewController and I simulate a memory warning in the PreferencesViewController my app crashes. This is not the case with the second method. The second method however makes my buttons looks strange during the flipping animation.</p>
  
  <p>Can someone tell me what is wrong and/or advise me on which method is <em>right</em>.</p>
  
  <p>Thanks</p>