public override async Task<FingerprintAuthenticationResult> AuthenticateNoDialogAsync(IAuthenticationFailedListener failedListener, CancellationToken cancellationToken) { using (var cancellationSignal = new CancellationSignal()) using (cancellationToken.Register(() => cancellationSignal.Cancel())) { var callback = new FingerprintAuthenticationCallback(failedListener); GetService().Authenticate(null, cancellationSignal, FingerprintAuthenticationFlags.None, callback, null); return await callback.GetTask(); } }