private void CaptureSignature()
        {
            signature = new SignaturePadView(new CGRect(100, 100, 400, 400))
            {
                StrokeWidth = 3f
            };
            var button = new UIButton(UIButtonType.RoundedRect);

            button.Frame = new CGRect(400, 505, 100, 50);
            button.SetTitle("Done", UIControlState.Normal);
            button.BackgroundColor = UIColor.DarkGray;
            button.TouchUpInside  += (sender, e) => {
                if (signature.IsBlank)
                {
                    return;
                }

                var image        = signature.GetImage();
                var imageEncoded = image.AsJPEG().GetBase64EncodedString(NSDataBase64EncodingOptions.None);

                var capture = new NSMutableDictionary();

                capture.Add(NSObject.FromObject("signature"), NSObject.FromObject(imageEncoded));
                capture.Add(NSObject.FromObject("refNum"), NSObject.FromObject(RefNumText.Text));
                capture.Add(NSObject.FromObject("amount"), NSObject.FromObject(AMOUNT));
                capture.Add(NSObject.FromObject("command"), NSObject.FromObject("capture"));

                CardReader.CaptureSignature(capture);

                button.RemoveFromSuperview();
                signature.RemoveFromSuperview();
            };

            View.AddSubview(signature);
            View.AddSubview(button);
        }