title: How do i do a flip animation on pop view controller?
body: <p>I have a flip animation which goes like this:</p>
  
  <pre><code>Picker *picker = [[Picker alloc] init];
  
              [self.navigationController pushViewController:picker animated:NO];
  
              [UIView animateWithDuration:0.5
                               animations:^{ 
                                   [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.navigationController.view cache:NO];
                                   } 
                               completion:^(BOOL finished){
                               }];
              [picker release];
  </code></pre>
  
  <p>This works perfectly. But when i want to do popViewController to get back, like this:</p>
  
  <pre><code>[self.navigationController popViewControllerAnimated:NO];
  
      [UIView animateWithDuration:0.5
                       animations:^{ 
  
                           [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.navigationController.view cache:NO];
                       } 
                       completion:^(BOOL finished){
                       }];
  </code></pre>
  
  <p>But this doesn't work, just goes back to the view without animating.</p>