Free draw view for Xamarin iOS

FreeDrawUIView.cs

using CoreGraphics;
using Foundation;
using UIKit;

namespace iOS
{
    public class FreeDrawUIView : UIView
    {
        UIBezierPath _path;

        public UIImage Image { get; private set; }

        public FreeDrawUIView()
        {
            _path = new UIBezierPath
            {
                LineWidth = 10
            };

            Image = new UIImage();

            MultipleTouchEnabled = false;
        }

        public override void Draw(CGRect rect)
        {
            base.Draw(rect);

            Image.DrawAsPatternInRect(rect);
            _path.Stroke();
        }

        public override void TouchesBegan(NSSet touches, UIEvent evt)
        {
            base.TouchesBegan(touches, evt);

            var touch = (UITouch)touches.AnyObject;
            var point = touch.LocationInView(this);

            _path.MoveTo(point);
        }

        public override void TouchesMoved(NSSet touches, UIEvent evt)
        {
            base.TouchesMoved(touches, evt);

            var touch = (UITouch)touches.AnyObject;
            var point = touch.LocationInView(this);

            _path.AddLineTo(point);
            SetNeedsDisplay();
        }

        public override void TouchesEnded(NSSet touches, UIEvent evt)
        {
            base.TouchesEnded(touches, evt);

            var touch = (UITouch)touches.AnyObject;
            var point = touch.LocationInView(this);

            _path.AddLineTo(point);
            DrawBitmap();
            SetNeedsDisplay();
            _path.RemoveAllPoints();
        }

        public override void TouchesCancelled(NSSet touches, UIEvent evt)
        {
            base.TouchesCancelled(touches, evt);

            TouchesEnded(touches, evt);
        }

        void DrawBitmap()
        {
            UIGraphics.BeginImageContextWithOptions(Bounds.Size, true, 0);
            UIColor.Black.SetStroke();

            if (Image != null)
            {
                var rectPath = UIBezierPath.FromRect(Bounds);

                UIColor.White.SetFill();

                rectPath.Fill();
            }

            Image.Draw(CGPoint.Empty);
            _path.Stroke();
            Image = UIGraphics.GetImageFromCurrentImageContext();
            UIGraphics.EndImageContext();
        }

        public void Clear()
        {
            _path.RemoveAllPoints();
            Image = new UIImage();
            SetNeedsDisplay();
        }
    }
}