Adding Force Touch

gistfile1.cs

    void DrawLine (CGPoint pt1, CGPoint pt2, UIColor color, nfloat forcePercentage)
		{
			UIGraphics.BeginImageContext (imgDraw.Frame.Size);

			using (var g = UIGraphics.GetCurrentContext ())
			{
				
				imgDraw.Layer.RenderInContext (UIGraphics.GetCurrentContext ());

				var path = new CGPath ();

				path.AddLines (new CGPoint[] { pt1, pt2 });
        
        //Calc Line width
				var size = 0.25f * Math.Pow (2, 1.5 * Math.Round (forcePercentage / 10));

				if (size > 25)
					size = 25;
				
				g.SetLineWidth ((nfloat)size);

				color.SetStroke ();
				Console.WriteLine (forcePercentage);
				Console.WriteLine (size);

				g.AddPath (path);
				g.DrawPath (CGPathDrawingMode.Stroke);

				imgDraw.Image = UIGraphics.GetImageFromCurrentImageContext ();
			}

			UIGraphics.EndImageContext ();
		}
		
    public override void TouchesMoved (NSSet touches, UIEvent evt)
		{
			foreach (UITouch touch in touches) 
			{
				UIColor color;
				colors.TryGetValue (touch.Handle, out color);

				DrawLine (touch.PreviousLocationInView (imgDraw), touch.LocationInView (imgDraw), color, CalcForcePercentage(touch));
			}
		}

		nfloat CalcForcePercentage(UITouch touch){
			return (touch.Force / touch.MaximumPossibleForce) * 100;
		}