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id title brief article sdk
Handle Annotation Click
This recipe shows how to add an annotation with a clickable button to a map.


To add an annotation and respond to touching a button within the annotation:

  1. Start with an existing MKMapView or review the Displaying a Location and Add an Annotation Recipes.

  2. Add an annotation as you normally would:

    var annotation = new BasicMapAnnotation
    	(new CLLocationCoordinate2D (48.857, 2.351), "Paris", "City of Light");
    mapView.AddAnnotation (annotation);
  3. Create a MKMapViewDelegate subclass (as shown). Notice how the GetViewForAnnotation method adds features such as the LeftCalloutAccessoryView and RightCalloutAccessoryView.

     protected class MapDelegate : MKMapViewDelegate
     	protected string annotationIdentifier = "BasicAnnotation";
     	UIButton detailButton;
     	MapViewController parent;
     	public MapDelegate(MapViewController parent)
     		this.parent = parent;
     	/// <summary>
     	/// This is very much like the GetCell method on the table delegate
     	/// </summary>
     	public override MKAnnotationView GetViewForAnnotation (MKMapView mapView, IMKAnnotation annotation)
     		// try and dequeue the annotation view
     		MKAnnotationView annotationView = mapView.DequeueReusableAnnotation(annotationIdentifier);
     		// if we couldn't dequeue one, create a new one
     		if (annotationView == null)
     			annotationView = new MKPinAnnotationView(annotation, annotationIdentifier);
     		else // if we did dequeue one for reuse, assign the annotation to it
     			annotationView.Annotation = annotation;
     		// configure our annotation view properties
     		annotationView.CanShowCallout = true;
     		(annotationView as MKPinAnnotationView).AnimatesDrop = true;
     		(annotationView as MKPinAnnotationView).PinColor = MKPinAnnotationColor.Green;
     		annotationView.Selected = true;
     		// you can add an accessory view, in this case, we'll add a button on the right, and an image on the left
     		detailButton = UIButton.FromType(UIButtonType.DetailDisclosure);
     		detailButton.TouchUpInside += (s, e) => {
     			Console.WriteLine ("Clicked");
     			//Create Alert
     			var detailAlert = UIAlertController.Create ("Annotation Clicked", "You clicked on " +
     				(annotation as MKAnnotation).Coordinate.Latitude.ToString() + ", " +
     				(annotation as MKAnnotation).Coordinate.Longitude.ToString(), UIAlertControllerStyle.Alert);
     			detailAlert.AddAction (UIAlertAction.Create ("OK", UIAlertActionStyle.Default, null));
     			parent.PresentViewController (detailAlert, true, null);
     		annotationView.RightCalloutAccessoryView = detailButton;
     		annotationView.LeftCalloutAccessoryView = new UIImageView(UIImage.FromBundle("29_icon.png"));
     		return annotationView;
     	// as an optimization, you should override this method to add or remove annotations as the
     	// map zooms in or out.
     	public override void RegionChanged (MKMapView mapView, bool animated) {}
  4. Finally, assign the delegate (prior to the code added earlier to add the annotation to the MKMapView instance):

     // assign the delegate, which handles annotation layout and clicking
     // the Delegate needs to be assigned before adding the annotation
     mapView.Delegate = new MapDelegate(this);
     var annotation = new BasicMapAnnotation
     	(new CLLocationCoordinate2D (48.857, 2.351), "Paris", "City of Light");
     mapView.AddAnnotation (annotation);