title: How to delete a user default value in NSUserDefaults?
body: <p>I.e., my app sets some standard default values at the beginning. Then those values may get overridden by the user. And when the user messes things up, I want to set those settings back to my app default values. As I understand it, the app defaults are a different dictionary than the user defaults, and the user defaults just override those app defaults. But I haven't seen methods for deleting the user defaults. Any idea?</p>