Xamarin Studio でコンポーネントを更新する方法 ref: http://qiita.com/amay077/items/2515dc0c01eede84bb19

PartOfMarkersViewController.cs

public override void ViewDidLoad ()
{
    base.ViewDidLoad ();

    var camera = CameraPosition.FromCamera (-37.81969, 144.966085, 4);
    var mapView = MapView.FromCamera (RectangleF.Empty, camera);

    var sydneyMarker = new Marker () {
        Title = "Sydney",
        Snippet = "Population: 4,605,992",
        Position = new CLLocationCoordinate2D (-33.8683, 151.2086),
        Map = mapView
    };

    var melbourneMarker = new Marker () {
        Title = "Melbourne",
        Snippet = "Population: 4,169,103",
        Position = new CLLocationCoordinate2D (-37.81969, 144.966085),
        Map = mapView
    };

    // Set the marker in Sydney to be selected
    mapView.SelectedMarker = sydneyMarker;

    View = mapView;
}