See Also: Pin Members
A Xamarin.Forms.Maps.Pin must have its Pin.Label property assigned before it is added to a map. If not, a ArgumentException is thrown.
C# Example
public static Page GetMapPage ()
{
var map = new Map (MapSpan.FromCenterAndRadius (new Position (37, -122), Distance.FromMiles (10)));
//If Label is not set, runtime exception
var pin = new Pin () {
Position = new Position (37, -122),
Label = "Some Pin!"
};
map.Pins.Add (pin);
var cp = new ContentPage {
Content = map,
};
return cp;
}