ArcGISWindowsPhoneSDK.PortalSearch.ShowSignInPageButton_Click C# (CSharp) Метод

        private void ShowSignInPageButton_Click(object sender, EventArgs e)
        {
            if ((ApplicationBar.Buttons[0] as IApplicationBarIconButton).Text.Equals("Sign In"))
            {
                SignInPage.IsOpen = true;
            }
            else //Sign Out
            {
                ResultsListBox.ItemsSource = null;
                WebmapContent.Children.Clear();
                var crd = IdentityManager.Current.FindCredential(DEFAULT_SERVER_URL, portal.CurrentUser.UserName);
                IdentityManager.Current.RemoveCredential(crd);
                portal.InitializeAsync(portal.Url, (credential, exception) =>
                {
                    if (exception == null)
                    {
                        ResetVisibility();
                        (ApplicationBar.Buttons[0] as IApplicationBarIconButton).Text = "Sign In";
                    }
                    else
                    {
                        MessageBox.Show("Error initializing portal : " + exception.Message);
                    }
                });
            }
        }