title: iOS - Check for Navigation bar
body: <p>I'm creating a library which will add a view at the bottom of the application (when my library is integrated in application).<br>
  I'm using view controller's view's frame parameter to get the size of the view and calculation my library's view frame according and showing it.<br>
  The problem is that when navigation bar is there, my view is going still below the actual view visible. So, i want to know whether current view controller is based on navigation controller or not and whether navigation bar is visible in that view or not. how can I find that?</p>