How can I implement "drag right to dismiss" a View Controller that's in a navigation stack?
<p>By default, if you drag right from the left edge of the screen, it will drag away the ViewController and take it off the stack.</p>

<p>I want to extend this functionality to the entire screen. When the user drags right anywhere, I'd like the same to happen.</p>

<p>I know that I can implement a swipe right gesture and simply call <code>self.navigationController?.popViewControllerAnimated(true)</code></p>

<p>However, there is no "dragging" motion. I want the user to be able to right-drag the view controller as if it's an object, revealing what's underneath. And, if it's dragged past 50%, dismiss it. (Check out instagram to see what I mean.)</p>