Regression: Torch not working on iOS

Enabling the torch does not work here, using an iPhone 6 with iOS 12.4.8. The same code (example below) works fine on Android.

In general the flash light is definitely working on the device. I have also tried Xamarin.Essentials.FlashLight with success.

Can anyone reproduce this issue?

Code example

ScannerPage.xaml

<ContentPage.Content>
    <Grid>
        <zxing:ZXingScannerView x:Name="scannerView"
                                IsAnalyzing="{Binding IsAnalyzing}" />

        <zxing:ZXingDefaultOverlay x:Name="scannerOverlay"
                                   TopText="{x:Static resx:AppResources.ScannerTopText}"
                                   BottomText="{x:Static resx:AppResources.ScannerBottomText}"
                                   ShowFlashButton="True" />
    </Grid>
</ContentPage.Content>

ScanPage.xaml.cs

using System;
using Xamarin.Forms;
using ZXing;
using ZXing.Mobile;

public partial class ScanPage
{
    public ScanPage()
    {
        this.InitializeComponent();
        this.InitializeScannerView();
    }

    protected override void OnAppearing()
    {
        base.OnAppearing();
        this.scannerView.IsScanning = true;
    }

    protected override void OnDisappearing()
    {
        this.scannerView.IsScanning = false;
        base.OnDisappearing();
    }

    private void InitializeScannerView()
    {
        this.scannerView.Options = new MobileBarcodeScanningOptions
        {
            PossibleFormats =  new[] { BarcodeFormat.QR_CODE }
        };

        this.scannerView.OnScanResult += this.ScannerViewOnOnScanResult;
        this.scannerOverlay.FlashButtonClicked += this.ScannerOverlayOnFlashButtonClicked;
    }

    private async void ScannerViewOnOnScanResult(Result result)
    {
        if (this.ViewModel.ScanResultCommand.CanExecute(result))
        {
            await this.ViewModel.ScanResultCommand.ExecuteAsync(result);
        }
    }

    private void ScannerOverlayOnFlashButtonClicked(Button sender, EventArgs eventArgs)
    {
        this.scannerView.ToggleTorch();
    }
}

Version info

Xamarin.Forms 4.8.0.1269 ZXing.Net.Mobile 3.0.0-beta5 ZXing.Net.Mobile.Forms 3.0.0-beta5

[LeroyStaines]

I’ve created a pull request for a fix for this:

https://github.com/Redth/ZXing.Net.Mobile/pull/1028

[radioactiveman]

@Softtinn: That’s the same workaround I am using meanwhile.

using Xamarin.Essentials;
...

private bool isTorchOn;

private async void ScannerOverlayOnFlashButtonClicked(Button sender, EventArgs eventArgs)
{
    if (Device.RuntimePlatform == Device.iOS)
    {
        // Workaround for torch not working on iOS.
        // Reported upstream as https://github.com/Redth/ZXing.Net.Mobile/issues/929
        await this.ToggleTorchOniOS();
    }
    else
    {
        this.scannerView.ToggleTorch();
    }
}

private async Task ToggleTorchOniOS()
{
    try
    {
        if (this.isTorchOn)
        {
            await Flashlight.TurnOffAsync();
        }
        else
        {
            await Flashlight.TurnOnAsync();
        }

        this.isTorchOn = !this.isTorchOn;
    }
    catch (Exception ex)
    {
        System.Diagnostics.Debug.WriteLine(ex);
    }
}