Backbutton on ZXing Scanner doesn´t works (Xamarin Forms)

Issue

im trying to implement a Barcode Scanner on my project in Xamarin Forms. When i press the back button on the scanning page my app crash. I am getting the following error: System.NullReferenceException: 'Object reference not set to an instance of an object.'

This is my code:

ScanService.cs

public interface ScanningService
{
    Task<string> ScanAsync();

}

My code behind:

var scanner = DependencyService.Get<ScanningService>();
        var result = await scanner.ScanAsync();
        if (result != null){.....}

QRscanningService (On Android):

   class QrScanningService : ScanningService
    {
       

        public async Task<string> ScanAsync()
        {

            var optionsCustom = new MobileBarcodeScanningOptions();

            var scanner = new MobileBarcodeScanner()
            {
                TopText = "Acerca la cámara",
                BottomText = "Toca la pantalla para enfocar",

            };
            var scanResult = await scanner.Scan(optionsCustom);

            return scanResult.Text;
        }

    }

Any contribution will be apreciated.

Solution

I solved it with the following code on my code behind:

var overlay = new ZXingDefaultOverlay
{
    ShowFlashButton = true,
    TopText = "Toca la pantalla para enfocar",
    BottomText = string.Empty
};

overlay.BindingContext = overlay;

scanPage = new ZXingScannerPage(null, overlay);
            
overlay.FlashButtonClicked += (s, ed) =>
{
    scanPage.ToggleTorch();
};

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

    Device.BeginInvokeOnMainThread(() =>
    {
        _ = Navigation.PopModalAsync();
        try
        {
            TxtidR.Text = result.Text;
        }
        catch (Exception)
        {
            throw;
        }
    });
};

await Navigation.PushModalAsync(scanPage);
var scanner = DependencyService.Get<ScanningService>();
}

I hope it works for you!

Answered By - Jair Olivares