title: How to use UIDocumentPickerViewController with UINavigationController?
body: <p>I'm trying to push a UIDocumentPickerViewController onto a UINavigationController's stack However, this results in what looks like two navigation bars. The top bar is the normal navigation bar of the navigation controller. Beneath that is the bar containing the document picker's Cancel and Done buttons. Clicking on the Cancel or Done buttons dismisses the entire view.</p>
  
  <p>Question: How can I properly include a UIDocumentPickerViewController onto a navigation controller's stack, so that the Cancel and Done buttons appear in the navigation bar, and cause the previous and next view controllers to appear?</p>