title: Animating UINavigationController's 'back' button
body: <p>I have a custom button on a view controller in the navigation controller's heirarchy, that when pressed, pops the visible view controller. </p>
  
  <p>I want to use UIView's <code>transform</code> property to animate the closing of the view controller. It works, but if I use `popViewControllerAnimated:YES', the default left slide of the animation is still there, though my custom transform also works. </p>
  
  <p>If I set <code>popViewControllerAnimated:NO</code> it doesn't animate anything at all. </p>
  
  <p>I also looked into using <code>CATransition</code> which works when I have <code>popViewControllerAnimated</code> set to <code>NO</code>, but there isn't a "zoom" effect that's part of the public API, and I don't want to use the private effect. Custom filters are also not available for iPhone, only OS X. </p>
  
  <p>So I guess my questions are:</p>
  
  <p>1) Is there a way to remove the the left slide in the default transition yet still have a custom animation using <code>transform</code>?</p>
  
  <p>2) Some way to use a custom filter for <code>CATransition</code>?</p>
  
  <p>3) If I use a private API for the zoom effect how likely will Apple toss my app in the rejection bin?</p>
  
  <p>Does anyone have a solution I'm overlooking?</p>