title: qlpreviewcontroller tap fullscreen in iOS
body: <p>what annoying me is a simple function but little references and posts from forums.</p>
  
  <p>I need a function like that in the default photos' app in iOS.</p>
  
  <p>When I'm browsing a photo, tap it, then the navigation bar and the tool bar on the bottom hides.</p>
  
  <p>How to realize it?</p>