title: NSNotificationCenter callback while app in background
body: <p>One question and one issue:
  I have the following code:</p>
  
  <pre><code>- (void) registerForLocalCalendarChanges
  {
      [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(localCalendarStoreChanged) name:EKEventStoreChangedNotification object:store ];
  
  }
  
  - (void) localCalendarStoreChanged
  {
      // This gets call when an event in store changes
      // you have to go through the calendar to look for changes
      [self getCalendarEvents];
  }
  </code></pre>
  
  <p>These methods are in a class/object called  CalendarEventReporter which contains the method getCalendarEvents (in the callback).</p>
  
  <p>Two things:
  1) If the app is in the background the callback does not run.  Is there a way to make it do that?
  2)  When I bring the app back into the foreground (after having changed the calendar on the device) the app crashes without any error message in the debug window or on the device.  My guess is that the CalendarEventReporter object that contains the callback is being garbage-collected.  Is that possible?  Any other thoughts on what might be causing the crash?  Or how to see any error messages?</p>