title: How to show a uiview alway on top?
body: <p>I want to show a <code>logo UIView</code> always on top when the app running,
  I know there is a way to do that,add same <code>UIView</code> to every <code>UIViewController</code>,
  but I think this is not the best way to do that.
  when i have lot of pages,and modify the <code>logo UIView</code>,must modify it every page.</p>
  
  <p>Did someone have better way to do this?
  thanks.</p>
  
  <p>look like this:</p>
  
  <p><img src="https://i.stack.imgur.com/itF2L.jpg" alt="sample image"></p>