title: How do I change the background of a UINavigationBar?
body: <p>I'd like to change the background of my UINavigationBar to a <code>[UIColor colorWithImage:]</code>, but it isn't working. What am I missing?</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>Once I've created my subclass, where do I set the UINavigationController to use it?</p>