title: UITabBarController app - how to call method between controllers?
body: <p>I have what I assume is a very simple problem, but the solution has escaped me.  I have a UITabBarController app.  There are two views, I'll call them A and B. And of course I have an AppDelegate class that initializes the tab bar.</p>
  
  <p>View B has a button called clearScore:.  When it is pressed, view B needs to invoke directly or indirectly clearScore: on view A.  Can someone show me the steps to make this happen?  Thanks for any help!</p>