title: ios: add compass to ARView
body: <p>I wanna add a compass to ARView in the following project: <a href="http://developer.apple.com/library/ios/#samplecode/pARk/Listings/pARk_ARView_m.html#//apple_ref/doc/uid/DTS40011083-pARk_ARView_m-DontLinkElementID_5" rel="nofollow">http://developer.apple.com/library/ios/#samplecode/pARk/Listings/pARk_ARView_m.html#//apple_ref/doc/uid/DTS40011083-pARk_ARView_m-DontLinkElementID_5</a></p>
  
  <p>I used <code>- (void) locationManager:(CLLocationManager *)manager didUpdateHeading:(CLHeading *)newHeading</code></p>
  
  <p>But it doesnt seem to be executed .
  Please Help me solve this.
  Thanks in advance</p>