title: Compiler error when calling dequeueReusableAnnotationViewWithIdentifier
body: <p>I'm trying to add a button on Annotation,
  but I'm getting an error on line:</p>
  
  <pre><code>MKPinAnnotationView *annotationView = (MKPinAnnotationView *)[MapView dequeueReusableAnnotationViewWithIdentifier:identifier];
  </code></pre>
  
  <p>which shows that: </p>
  
  <blockquote>
    <p>no known class method for the selector dequeueReusableAnnotationViewWithIdentifier.</p>
  </blockquote>
  
  <p>I really don't know how to fix it And I appreciate any help.</p>
  
  <pre><code>-(MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id &lt;MKAnnotation&gt;)annotation {
  
  static NSString *identifier = @"MyLocation";
  if ([annotation isKindOfClass:[MapAnnotation class]]) {
  
      MKPinAnnotationView *annotationView = (MKPinAnnotationView *)[MapView dequeueReusableAnnotationViewWithIdentifier:identifier];
  
      if (annotationView == nil) {
          annotationView = [[MKPinAnnotationView alloc] 
                            initWithAnnotation:annotation 
                            reuseIdentifier:identifier];
      } else {
          annotationView.annotation = annotation;
      }
  
      annotationView.enabled = YES;
      annotationView.canShowCallout = YES;
  
      // Create a UIButton object to add on the 
  
      UIButton *leftButton = [UIButton buttonWithType:UIButtonTypeInfoDark];
      [leftButton setTitle:annotation.title forState:UIControlStateNormal];
      [annotationView setLeftCalloutAccessoryView:leftButton];
  
      return annotationView;
  }
  }
  </code></pre>