title: iOS set ViewController and AppDelegate as listeners to CoreLocation model class
body: <p>How do you set up the <code>AppDelegate</code> and a <code>ViewController</code> to be listeners to a model corelocation class? What are the proper design choices??</p>
  
  <p>I'm interested in having a model class to implement <code>CoreLocation</code> and location updates. I'm guessing this class should be a <code>sharedSingleton</code>, because both my <code>AppDelegate</code> and <code>ViewController</code> wish to access it.</p>
  
  <p>When my <code>viewController</code> calls it, I want the <code>CLLocationManager</code> to use <code>startUpdatingLocation</code>.</p>
  
  <p>When the app goes into background, I want to monitor location updates in the AppDelegate using startMonitoringSignificantLocationChanges.</p>
  
  <p>My question is, how do I set up the model class to handle these different types of location updates, as well as notify the ViewController or AppDelegate that a new location is found? Using <code>NSNotification</code>? Delegation doesn't seem to work because it's a one-to-one relationship.</p>
  
  <p>Appreciate your help on figuring out how to design this.</p>
  
  <p>Thanks!</p>