title: Pass touches through a UIViewController
body: <p>I have a view controller that I overlay on top of another view controller. I just need the top view controller so I can overlay a temporary pop up notification, and having an overlayed VC allows me to present this over a UITableViewController as you can't add subviews to tableview controllers directly. </p>
  
  <p>Is it possible to interact with the bottom view controller while it has another view controller covering it. If this were a view or a window you would achieve this by setting user interaction to false or using hitTest but neither of these approaches works for a view controller.</p>