PickerSelected.cs

private void OnStateSelected(string stateName)
{
  if (this.currentStateOverlay != null)
  {
	this.mainView.MapView.RemoveOverlay(this.currentStateOverlay);
  }

  State selectedState = this.states.First(state => state.Name == stateName);		

  this.mainView.MoveMapIntoViewAndPickerOutOfView();

  CLLocationCoordinate2D[] stateBoundary = selectedState.Boundary.Select(coord => new CLLocationCoordinate2D(coord.Latitude, coord.Longitude)).ToArray();
  this.currentStateOverlay = MKPolygon.FromCoordinates(stateBoundary);
  this.currentStateOverlay.Title = selectedState.Name;
  this.mainView.MapView.AddOverlay (this.currentStateOverlay);
}