title: Objective C: How to implement MapKit Method - (NSSet *)annotationsInMapRect:(MKMapRect)mapRect
body: <p>I am trying to implement the method below to select the set of annotations in the visible region of my map.</p>
  
  <pre><code>- (NSSet *)annotationsInMapRect:(MKMapRect)mapRect
  </code></pre>
  
  <p>I added the line in my code as such</p>
  
  <pre><code>NSSet *nearbySet = [self annotationsInMapRect:self.mapView.frame];
  </code></pre>
  
  <p>My app is crashing because of this. Can anyone advise on how I should use the above method correctly?</p>
  
  <p>EDIT:
  Stack Trace is as follows:</p>
  
  <pre><code>Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[CarParkTableViewController annotationsInMapRect:]: unrecognized selector sent to instance 0x187b60'
  </code></pre>
  
  <p>Thanks</p>
  
  <p>Zhen Hoe</p>