protected override async void OnAppearing()
        {
            base.OnAppearing();

            var authType= await Plugin.Fingerprint.CrossFingerprint.Current.GetAuthenticationTypeAsync();
            if(authType==AuthenticationType.Fingerprint)
            {
                lblAuthenticationType.Text = "Auth Type: " + authType;

                await AuthenticateAsync("Authendicate with Touch ID");
            }
           
        }

        private async Task AuthenticateAsync(string reason, string cancel = null, string fallback = null, string tooFast = null)
        {
            _cancel = false ? new CancellationTokenSource(TimeSpan.FromSeconds(10)) : new CancellationTokenSource();
            
            var dialogConfig = new AuthenticationRequestConfiguration("My App", reason)
            { 
                CancelTitle = cancel,
                FallbackTitle = fallback,
                AllowAlternativeAuthentication = true,
                ConfirmationRequired = false
            };

            dialogConfig.HelpTexts.MovedTooFast = tooFast;
            var result = await Plugin.Fingerprint.CrossFingerprint.Current.AuthenticateAsync(dialogConfig, _cancel.Token);
            await SetResultAsync(result);
        }