title: Getting reference to the top-most view/window in iOS application
body: <p>I'm creating a reusable framework for displaying notifications in an iOS application. I'd like the notification views to be added over the top of everything else in the application, sort of like a UIAlertView. When I init the manager that listens for NSNotification events and adds views in response, I need to get a reference to the top-most view in the application. This is what I have at the moment:</p>
  
  <pre><code>_topView = [[[[UIApplication sharedApplication] keyWindow] subviews] lastObject];
  </code></pre>
  
  <p>Would this work for any iOS application or is their a safer/better way to get the top view?</p>