Use torch while scanning barcode - xamarin.forms

Question

I'm using ZXing.Mobile.Forms to scan the barcodes.
I would like to turn the torch on while scanning the barcodes. I tried ToggleTorch() but i dont see the torch light.
Please help to overcome this scenario.
Here is my code:
var scanner = new ZXing.Mobile.MobileBarcodeScanner();
scanner.ToggleTorch();
var option = new ZXing.Mobile.MobileBarcodeScanningOptions { UseCode39ExtendedMode = true, TryHarder = true, PureBarcode = true, };
var result = await scanner.Scan(option);
if (result != null)
await Application.Current.MainPage.DisplayAlert(title, result.Text, "Cancel");
await Application.Current.MainPage.Navigation.PopAsync(true);

Answer 1

OK here is the main idea which does what you want, in an MVVM manner:
XAML:
<zxing:ZXingScannerView x:Name="ScannerView"
IsTorchOn="{Binding IsTorchOn}"
IsScanning="{Binding IsScanning}"
IsAnalyzing="{Binding IsAnalyzing}"
ScanResultCommand="{Binding OnScanResult}"/>
Code-behind:
public partial class BarcodeScannerPage
{
private BarcodeScannerPageModel _pageModel;
public BarcodeScannerPage()
{
InitializeComponent();
}
protected override void OnAppearing()
{
base.OnAppearing();
if(_pageModel == null) return;
_pageModel.IsScanning = true;
_pageModel.IsAnalyzing = true;
_pageModel.IsTorchOn= true;
}
protected override void OnBindingContextChanged()
{
base.OnBindingContextChanged();
_pageModel = BindingContext as BarcodeScannerPageModel;
}
}
Page model:
public class BarcodeScannerPageModel
{
#region instance variables
private bool _isScanning;
private bool _isAnalyzing;
private bool _isTorchOn;
#endregion
public BarcodeScannerPageModel()
{
IsTorchOn = true;
}
public bool IsScanning
{
get => _isScanning;
set
{
_isScanning = value;
RaisePropertyChanged();
}
}
public bool IsAnalyzing
{
get => _isAnalyzing;
set
{
_isAnalyzing = value;
RaisePropertyChanged();
}
}
public ICommand OnScanResult
{
get
{
return new Command(async (result) =>
{
if (result.ToString().IsNullOrEmpty()) return;
Device.BeginInvokeOnMainThread(async () =>
{
IsAnalyzing = false;
//your code here...
});
});
}
}
public bool IsTorchOn
{
get => _isTorchOn;
set
{
_isTorchOn = value;
RaisePropertyChanged();
}
}
}
Here I assumed MVVM is set and used correctly including "PropertyChanged" events and setting "BindingContext". More info:
MVVM
From Data Bindings to MVVM
MVVM & Data Binding with Xamarin.Forms
Using some MVVM frameworks such as FreshMvvm can make things easier.