title: UINavigationContoller interactivePopGestureRecognizer inactive when navigation bar is hidden
body: <p>I have a view controller which is nested within a <code>UINavigationController</code>.</p>
  
  <p>I have implemented the iOS 7 interactivePopGestureRecognizer to enable the user to gesture to pop a VC off the stack.</p>
  
  <p>Within the VC i have a scrollview and whilst the user is not at the top of the scrollview I hide all the chrome (Navigation bar and status bar) to place focus on the content.</p>
  
  <p>However with the navigation bar hidden, the interactivePopGestureRecognizer is not working.</p>
  
  <p>I have tried enabling it after it has disappeared and verified it is not nil, however it still doesn't work.</p>
  
  <p>Is there anything I am missing?</p>