title: Get reference to top viewcontroller in iOS
body: <p>How do I get reference to top visible view controller in my app. I saw some solutions which make use of navigationcontroller.[top|visible]viewcontroller. But I don't use navigation controllers in my app.</p>
  
  <p>This seems like a pretty common use case, and I find it strange it is difficult to get access to top|visible view controller</p>