title: Display new iOS UIView everywhere in existing app
body: <p>I simply want to display a basic UIView in the top right corner of an existing app. 
  The app is very complex with many different view controllers and layouts. 
  What is the easiest way to create a view once and make sure it stays on screen over the top of any other view that appears?</p>
  
  <p>The only way I can think of is inserting the view into every view controller. But I need to maintain the same instance of the view throughout the app and I don't want to have to do this every time we add a new view controller to the app.</p>