title: How to pop to an arbitrary view controller from anywhere in a navigation stack
body: <p>I'm working on a navigation based app, and I chose it so that I can push and pop controllers on and off the stack.  It's easy enough to move forward - just push a new controller.  And moving back is easy as long as you go to the root view controller.  There is a method called <code>popToViewController:animated,</code> but I didn't create the controller I want to pop to from within my current view controller, so the compiler complains that I haven't declared it.  I know it's the second controller on the stack (one above the root).  Can I use that to get there?</p>