You must disable foreground dispatching while your activity is still resumed

Description

Had anyone seen this ? “You must disable foreground dispatching while your activity is still resumed”

On Android - I need nfc scanning to listen for the tag only when button is pressed. iOS - works ok for below code.

Steps to Reproduce

1. Android app, when listening for tag one after another.
2. below is the code from view model

	private async Task ScanAPointAsync()
        {
            IsBusy = true;
            try
            {
                string[] options = new string[] { "Scan Barcode" };
                if (CrossNFC.IsSupported && CrossNFC.Current.IsAvailable)
                {
                    options = new string[] { "Scan Barcode", "Read a Tag" };
                }

                var result = await page.DisplayActionSheet("Select", "Cancel", null, options);
                if (result == "Read a Tag")
                {
                    if (CrossNFC.Current.IsEnabled)
                    {
                        CrossNFC.Current.OnMessageReceived += Current_OnMessageReceived;
                        CrossNFC.Current.StartListening();
                    }
                    else
                    {
                        await page.DisplayAlert("Enable NFC", "Please enable NFC on your phone.", "OK");
                    }
                }
            }
            catch (Exception)
            {
                await page.DisplayAlert("Error", "Something went wrong, Please try again.", "OK");
            }
            finally
            {
                IsBusy = false;
            }
        }

	private async void Current_OnMessageReceived(ITagInfo tagInfo)
        {
            if (tagInfo != null)
            {
		string serialNumber = tagInfo.SerialNumber;
		
		// do something more here

                CrossNFC.Current.OnMessageReceived -= Current_OnMessageReceived;
                CrossNFC.Current.StopListening();
            }
        }

Expected Behavior

shouldnt crash

Actual Behavior

App Crashes with “You must disable foreground dispatching while your activity is still resumed”

Basic Information

• Version with issue: 0.1.16
• Last known good version: NA
• IDE: Visual Studio
• Platform Target Frameworks:
  • Android: 10.0

[kberawala]

You probably need to unsubscribe and stop listening in the main thread like this:

Device.BeginInvokeOnMainThread(() =>
{
    CrossNFC.Current.OnMessageReceived -= Current_OnMessageReceived;
    CrossNFC.Current.StopListening();
});

It worked. Thanks

[franckbour]

You probably need to unsubscribe and stop listening in the main thread like this:

Device.BeginInvokeOnMainThread(() =>
{
    CrossNFC.Current.OnMessageReceived -= Current_OnMessageReceived;
    CrossNFC.Current.StopListening();
});