PulsingHaloLayer for pierceboggan

PulsingHaloLayer

using System;
using System.Collections.Generic;
using System.Linq;
using MonoTouch.Foundation;
using MonoTouch.UIKit;
using MonoTouch.CoreAnimation;
using System.Drawing;
using System.Threading.Tasks;

namespace PulsingHaloLayer
{
	public class PulsingHaloLayer : CALayer
	{
		CAAnimationGroup animationGroup;
		double animationDuration;
		double pulseInterval;
		float radius;

		public PulsingHaloLayer ()
		{

			this.ContentsScale = UIScreen.MainScreen.Scale;			
			this.Opacity = 0;
			// default
			this.radius = 60;
			this.animationDuration = 3;
			this.pulseInterval = 0;
			this.BackgroundColor = UIColor.FromRGBA (0, 0.478f, 1, 1).CGColor;
			Task.Factory.StartNew(Dispatcher);
			//await DispatchAsync();
			/*
				if(this.pulseInterval != INFINITY) {

					dispatch_async(dispatch_get_main_queue(), ^(void) {

						[this addAnimation:this.animationGroup forKey:@"						pulse"];
					});
				}
			});
			*/
		}
		async void Dispatcher()
		{
			await DispatchAsync ();
		}
		public async Task setRadius(float raggio, UIColor color){
			this.BackgroundColor = color.CGColor;//UIColor.FromRGBA (0, 0.487f, 1.0f, 1.0f).CGColor;
			radius = raggio;

			PointF tempPos = this.Position;

			float diameter = this.radius * 2;

			this.Bounds =  new RectangleF(0, 0, diameter, diameter);
			this.CornerRadius = this.radius;
			this.Position = tempPos;
		}
		public async Task DispatchAsync()
		{
	
			this.animationGroup = CAAnimationGroup.CreateAnimation ();
			this.animationGroup.Duration = this.animationDuration + this.pulseInterval;
			this.animationGroup.RepeatCount = float.MaxValue;
			this.animationGroup.RemovedOnCompletion = false;
			this.animationGroup.TimingFunction = CAMediaTimingFunction.FromName (CAMediaTimingFunction.Linear);

			var scaleAnimation = new CABasicAnimation {
				From = NSNumber.FromFloat (0),
				To = NSNumber.FromFloat (50),
				KeyPath = "transform.scale.xy",
				Duration = this.animationDuration
			};
			var opacityAnimation = (CAKeyFrameAnimation)CAKeyFrameAnimation.FromKeyPath ("opacity");

			opacityAnimation.Duration = this.animationDuration;
			opacityAnimation.Values = new NSNumber[]{
				NSNumber.FromFloat (0.45f),
				NSNumber.FromFloat (0.45f),
				0
			};
			/*
			opacityAnimation.KeyTimes = new NSNumber[]{
				0,
				NSNumber.FromFloat (0.2f),
				1
			};
			*/
			opacityAnimation.RemovedOnCompletion = false;


			this.animationGroup.Animations = new CAAnimation [] { scaleAnimation, opacityAnimation};
			if (pulseInterval != double.MaxValue) {
				await aggiungiAnimazione ();
			}
		}
		public async Task aggiungiAnimazione(){
			this.AddAnimation (animationGroup, "pulse");
		}

	}
}

______________________
HOW TO USE

 public override void ViewDidLoad()
{
	base.ViewDidLoad();
	PulsingHaloLayer halo = new PulsingHaloLayer ();
	UIButton btnricerca = new UIButton (UIButtonType.Custom);
	btnricerca.Frame = new RectangleF(120,390,80,80);

	halo.Position = btnricerca.Center;
	this.View.Layer.InsertSublayerBelow (halo, btnricerca.Layer); 
	btnricerca.BackgroundColor = UIColor.White;

	// Put on a rounded border
	btnricerca.Layer.BorderWidth = 2;
	btnricerca.Layer.BorderColor = new MonoTouch.CoreGraphics.CGColor(0,0,0,0.9f);
	btnricerca.Layer.CornerRadius =40;
	halo.setRadius(0.5f * 3, UIColor.Yellow);
	
	
	
	// Setup the title text color
	btnricerca.SetTitleColor(UIColor.DarkGray, UIControlState.Normal);
	View.AddSubview (btnricerca);
}