title: Custom transitionFromViewController throws error
body: <p>I need to create a method in my navigation controller similar to the <strong>pushViewController:viewController animated:YES</strong> method but i need to add 80px to the top of the frames of the view controllers whilst it does the left to right transition. However the method below is throwing the following error:</p>
  
  <blockquote>
    <p>Parent view controller is using legacy containment in call to
    -[UIViewController transitionFromViewController:toViewController:duration:options:animations:completion:]'</p>
  </blockquote>
  
  <pre><code>- (void)transitionFrom:(UIViewController *)oldController To:(UIViewController *)newController
  {
      [self addChildViewController:newController];
      //[self configureChild:newController];
      [newController.view setFrame:CGRectMake(320, 80, oldController.view.frame.size.width, oldController.view.frame.size.height)];
      [self transitionFromViewController:oldController
                        toViewController:newController
                                duration:0.5
                                 options:UIViewAnimationOptionTransitionFlipFromLeft
                              animations:^{
                                  [oldController.view setFrame:CGRectMake(-320, 80, oldController.view.frame.size.width, oldController.view.frame.size.height)];
                                  [newController.view setFrame:CGRectMake(0, 80, newController.view.frame.size.width, newController.view.frame.size.height)];
                              }
                              completion:^(BOOL finished){
                                  //[oldController willMoveToParentViewController:nil];
                                  [oldController removeFromParentViewController];
                                  [newController didMoveToParentViewController:self];
                              }];
  }
  </code></pre>