title: Firing events accross multiple viewcontrollers from a thread in the appdelegate
body: <p>I have an NSAutoreleasePool thread that is designed to pull information down from a web service, i have the web service code working nicely and i can trigger the thread to start in a view controller without any trouble, in fact its working quite nicely.</p>
  
  <p>I want to:</p>
  
  <ul>
  <li>move the thread instantiation to the appDelegate - easy!</li>
  <li>have it run periodically and somehow tell the viewcontrollers under it (5 - 10) if new information is downloaded</li>
  <li>have the capacity to manually execute the thread outside of the scheduler</li>
  </ul>
  
  <p>I can fire up a method on the appdelegate using performSelectorOnMainThread but how i can get my child view controllers to "subscribe" to a method on the appdelegate?</p>