title: NavController push from subview
body: <p>I got an application with a tabbar and a navigation controller for one of the tab view.
  The Navigation controller is pushing several views and one of them has a button which permits to add a subview (I am actually displaying a popup message -not an uialert- when pushing that button).</p>
  
  <p>The problem is that I would like now to be able to push a new view controller once I pushed a button in the subview...</p>
  
  <p>I cannot find my navcontroller, even when I use the pushmethod of appdelegate.tabbar.navigationController</p>
  
  <p>Does one of you have easy idea about how to implement that ?</p>
  
  <p>Thanks a lot !</p>