Xamarin.Forms 将 IsEnable 设置为 true 不起作用

Question

I am using Xamarin.Forms and I am trying to use disable a button and then enable it when the button action is finished, when I disable it, the button does in fact become disabled, but when I enable it, its still disabled, what am I doing wrong? Here is my full method:

private void OnCameraScan(object sender, EventArgs e)
{
    ScanLicence.IsEnabled = false;

    var barcodeScanView = new ZXing.Net.Mobile.Forms.ZXingScannerView
    {
        HeightRequest = 200
    };

    ScannerWrapper.HeightRequest = 200;
    ScannerWrapper.IsVisible = true;


    var options = new MobileBarcodeScanningOptions
    {
        TryHarder = true,
        CameraResolutionSelector = HandleCameraResolutionSelectorDelegate,
        PossibleFormats = new List<BarcodeFormat> { BarcodeFormat.PDF_417 },
    };

    barcodeScanView.OnScanResult += (result) =>
    {
        barcodeScanView.IsScanning = false;

        Console.WriteLine(result);

        var data = result.Text.Split('\n');

        foreach (var line in data)
        {

            if (line.Length > 3)
            {
                var code = line.Substring(0, 3);
                var value = line.Substring(3);

                Xamarin.Forms.Device.BeginInvokeOnMainThread(() =>
                {
                    switch (code)
                    {
                        case "DCT":
                            userClass.Customer_Name = value.Trim();
                            Customer_Name.Text = value.Trim();
                            break;
                        case "DCS":
                            userClass.Customer_LName = value.Trim();
                            Customer_LName.Text = value.Trim();
                            break;
                        case "DAI":
                            userClass.City = value.Trim();
                            City.Text = value.Trim();
                            break;
                        case "DAG":
                            userClass.Address1 = value.Trim();
                            Address1.Text = value.Trim();
                            break;
                        case "DAK":
                            userClass.Zip = value.Trim();
                            Zip.Text = value.Trim();
                            break;
                    }

                });


            }
        }

        ScanLicence.IsEnabled = true;


    };

    barcodeScanView.Options = options;
    barcodeScanView.IsScanning = true;

    ScannerWrapper.Children.Add(barcodeScanView);

}

The button in question is ScanLicence .

<Button x:Name="ScanLicence" Text="Scan Licence" Clicked="OnCameraScan" Style="{StaticResource ButtonStyle}" WidthRequest="50" />

This is for an iOS application.

Answer 1

You can try cast the object which invokes the event to "Button" and then disable it. At the end of your code you could have something like this:

// Safe casting to Button instance.
Button button = sender as Button;

// Make sure the cast didn't return a null value
if(button == null) return;

// Set enable to true
button.IsEnabled = true; // You can also use button.IsEnabled = !button.IsEnabled 

Make sure that you don't have any kind of binding of the button, it may be ignoring property assigment in code behind.