static void TransformPoints(CoreGraphics.CGAffineTransform t, PointF [] pts) { for (int i = 0; i < pts.Length; ++i) { var p = pts [i]; var cgp = t.TransformPoint(new CoreGraphics.CGPoint(p.X, p.Y)); pts [i] = new PointF((float)cgp.X, (float)cgp.Y); } }