title: pushViewController with scaling animation, that shows background
body: <p>I have finding way to call pushViewController with scaling animation, 
  like facebook iPhone app main menu icon click animation. 
  (new viewController is popup from center, and it scales to original size.)</p>
  
  <p>I searched several way to change animation of pushViewController. </p>
  
  <p>First, I tried this:</p>
  
  <pre><code>viewController.view.transform = CGAffineTransformMakeScale(0.5f, 0.5f);
  [UIView animateWithDuration:0.5f animations:^{ 
      viewController.view.transform = CGAffineTransformMakeScale(1.0f, 1.0f);
  }];
  [self.navigationController pushViewController:viewController animated:NO];
  </code></pre>
  
  <p>but there is problem, 
  old viewController is disappeared when animation starts, there's only white background. </p>
  
  <p>If I use CATransition to change animation, 
  I can show both old &amp; new viewController both, 
  but there's no scaling animation, only move in, push in, fade in animations. </p>
  
  <p>I want to show both new &amp; old view controller like CATransition animations, 
  and need the way to implement my custom animation.</p>
  
  <p>Here is my last suggestion, dirty way:</p>
  
  <pre><code>[self.view addSubview:viewController.view];
  viewController.view.transform = CGAffineTransformMakeScale(0.5f, 0.5f);
  [UIView animateWithDuration:0.5f
                        delay:0.0f
                      options:UIViewAnimationCurveEaseInOut
                   animations:^{
      viewController.view.alpha = 1.0f;
      viewController.view.transform = CGAffineTransformMakeScale(1.0f, 1.0f); 
  } completion:^(BOOL finished) {
      [self.navigationController pushViewController:viewController animated:NO];
      [viewController release];
  }];
  </code></pre>
  
  <p>First, I added new viewController.view as subview, I can show animation with new &amp; old view both.
  When animation is ended, pushViewController later. </p>
  
  <p>this way I can implement what I thought, 
  but I think it is dirty way, and there's remain problem:</p>
  
  <p>Navigation bar items are not change immediately, It is changed after animation ends. </p>
  
  <p>Is there any simple, clear way to implement this animation? 
  I think it is impossible to do that without change original implentation of pushViewController, should I do subclassing pushViewController?</p>
  
  <p>Thanks to read, and your help. </p>