Sending updates via MessagingCenter

When a node is created or removed, we need to send statistics to anything that is listening. To do this, we need a new method that will go through the scene and count how many planes and boxes we have and then send a message. Let's set this up by going through the following steps:

1. In the WhackABox project, open the Game.cs file.
2. Add a method called SendStats() anywhere in the class, as shown in the following code block:

private void SendStats()
{
    var planes = scene.Children.OfType<PlaneNode>();
    var boxCount = 0;
 
    foreach (var plane in planes)
    {
        boxCount += plane.Children.Count(e => e.Name == "Box");
    }
 
    var stats = new GameStats()
    {
        NumberOfBoxes = boxCount,
        NumberOfPlanes = planes.Count()
    };
 
    Xamarin.Forms.Device.BeginInvokeOnMainThread(() =>
    {
        Xamarin.Forms.MessagingCenter.Send(this, "stats_updated",  
        stats);
    });
} 

The method checks...