ZXing OnScanResult is called twice on Xamarin.Forms - xamarin.forms

Question

I have a Xamarin.Forms application. I use ZXing.Mobile.Forms to scan a QR code; however, when I point the camera to a QR code the OnScanResult event is called twice. This is my code, a faithful reproduction of the one suggested here:
private async void onScanQRCode(object sender, EventArgs e)
{
var scanPage = new ZXingScannerPage(); // executed just once
scanPage.OnScanResult += (result) => {
// Stop scanning
scanPage.IsScanning = false; // executed twice (confused)
// Pop the page and show the result
Device.BeginInvokeOnMainThread(() => {
Navigation.PopAsync();
/* Business code */
Account scannedAccount = URLInterpreter.Accept(result.Text);
ViewModel.ProcessNewAccount(scannedAccount);
/* End of business code */
});
};
// Navigate to our scanner page
await Navigation.PushAsync(scanPage);
}
And this is the XAML for the button that calls the method above:
<Button x:Name="btnScanCode" Text="Scan QR Code" Clicked="onScanQRCode" />
Any pointers?
UPDATE
Apparently, this only happens when I'm debugging the app and the phone is connected to Visual Studio. If I launch the app without attaching the debugger, the event is fired once.

Answer 1

I had the same issue, this answer helped me to resolve it: Xamarin.Forms ZXing.Net.Mobile loosing current page after scan result on iOS 10
Your code should be:
private async void onScanQRCode(object sender, EventArgs e)
{
var scanPage = new ZXingScannerPage();
bool scanFinished = false;
scanPage.OnScanResult += (result) => {
// Stop scanning
scanPage.IsScanning = false;
// Pop the page and show the result
Device.BeginInvokeOnMainThread(async () => {
if (!scanFinished)
{
scanFinished = true;
Account scannedAccount = URLInterpreter.Accept(result.Text);
ViewModel.ProcessNewAccount(scannedAccount);
await Navigation.PopAsync();
}
});
};
// Navigate to our scanner page
await Navigation.PushAsync(scanPage);
}
I tested on iOS 10.3.1 and ZXing.Net.Forms.Mobile 2.2.9.