CustomLabelRenderer.cs

using Xamarin.Forms.Platform.iOS;
using CoreGraphics;
using UIKit;
using Xamarin.Forms;
using FormsTestApp.iOS;
using FormsTestApp;

[assembly: ExportRenderer(typeof(CrossedOutLabel), typeof(CustomLabelRenderer))]
namespace FormsTestApp.iOS
{
	public class CustomLabelRenderer : LabelRenderer
	{
		public override void Draw (CGRect rect)
		{
			using (var context = UIGraphics.GetCurrentContext ()) {
				ClearCanvas (context, rect);
				DrawLine (context, rect);
			}
		}

		static void ClearCanvas (CGContext context, CGRect rect)
		{
			context.SetFillColor (Color.White.ToCGColor ());
			context.FillRect (rect);
		}

		void DrawLine (CGContext context, CGRect rect)
		{
			var label = Element as CrossedOutLabel;

			context.SetLineWidth (1);
			context.SetStrokeColor (label.LineColor.ToCGColor ());
			context.SetFillColor (label.BackgroundColor.ToCGColor ());
			context.MoveTo (25, 15);
			context.AddLineToPoint (100, -8);
			context.DrawPath (CGPathDrawingMode.FillStroke);
		}
	}
}