Login and Logout from Facebook in Windows Phone 7

• Download source code - 131.2 KB

Introduction

This tip describes how to Logout a Facebook user which is authenticated or connected with a Windows 7 phone application.

Background

Last week, when I was developing a Windows Phone 7 application with Facebook integration, at some point I needed code to logout from an authenticated or connected Facebook user. I did a lot of search on Google but no solution was found. So I did a tricky thing in my Windows Phone 7 application.

Login to Facebook

This block will describe how to integrate a Facebook login with a Windows Phone 7 application:

private static readonly Uri FacebookCookieUri = 
          new Uri("https://login.facebook.com/login.php");
private HttpWebRequest _webRequest;
private CookieContainer _cookieContainer = new CookieContainer();

private FacebookClient _asyncFbClient;
private string _appID = "xxxxxxxx";
private string _appSecret = "xxxxxxxxxxxxxx";

private void button1_Click(object sender, RoutedEventArgs e)
{
    string[] extendedPermissions = new[] { "user_about_me", "publish_stream" };

    var oauth = new FacebookOAuthClient { AppId = _appID, AppSecret = _appSecret };
    var parameters = new Dictionary<string, object>
                    {
                        {"response_type", "token"},
                        {"display", "touch"}                                        
                    };
    if (extendedPermissions != null && extendedPermissions.Length > 0)
    {
        var scope = new StringBuilder();
        scope.Append(string.Join(",", extendedPermissions));
        parameters["scope"] = scope.ToString();
    }

    var loginUrl = oauth.GetLoginUrl(parameters);
    webBrowser1.Navigated += 
      new EventHandler<System.Windows.Navigation.NavigationEventArgs>(CheckForAuth);
    webBrowser1.Navigate(loginUrl);
    webBrowser1.Visibility = Visibility.Visible;
}

private void CheckForAuth(object sender, System.Windows.Navigation.NavigationEventArgs e)
{
    FacebookOAuthResult result;
    if (FacebookOAuthResult.TryParse(e.Uri, out result))
    {
        if (result.IsSuccess)
        {
            webBrowser1.Visibility = Visibility.Collapsed;
            IsolatedStorageSettings Settings = IsolatedStorageSettings.ApplicationSettings;
            if (Settings.Contains("MyFacebookAccessToken"))
                Settings["MyFacebookAccessToken"] = result.AccessToken;
            else
                Settings.Add("MyFacebookAccessToken", result.AccessToken);
            //      MessageBox.Show(result.AccessToken);
            Settings.Save();
            _asyncFbClient = new FacebookClient(result.AccessToken);
            _asyncFbClient.GetCompleted += 
              new EventHandler<FacebookApiEventArgs>(_asyncFbClient_GetCompleted);
            _asyncFbClient.GetAsync("/me");
        }
        else
        {
            webBrowser1.Visibility = Visibility.Visible;
        }
    }
}

void _asyncFbClient_GetCompleted(object sender, FacebookApiEventArgs e)
{
    FacebookUser _fbUser = e.GetResultData<FacebookUser>();

    Deployment.Current.Dispatcher.BeginInvoke(() =>
    {
        MessageBox.Show(_fbUser.ID);
        //  fbName.Text = _fbUser.Name;
        //    BitmapImage bi = new BitmapImage(new Uri(
        //         "https://graph.facebook.com/" + _fbUser.ID + "/picture"));
        //   fbAvatar.Source = bi;
        // HideFacebookLogin.Begin();
    });
    _asyncFbClient.GetCompleted -= _asyncFbClient_GetCompleted;
}

Logout from Facebook

private void button2_Click(object sender, RoutedEventArgs e)
{
    webBrowser1.Navigated += 
      new EventHandler<System.Windows.Navigation.NavigationEventArgs>(CheckForout);
    webBrowser1.Navigate(new Uri("http://m.facebook.com/logout.php?confirm=1"));
    webBrowser1.Visibility = Visibility.Visible;
}

private void CheckForout(object sender, System.Windows.Navigation.NavigationEventArgs e)
{

    string fbLogoutDoc = webBrowser1.SaveToString();

    Regex regex = new Regex
    ("\\<a href=\\\"/logout(.*)\\\".*data-sigil=\\\"logout\\\"");
    MatchCollection matches = regex.Matches(fbLogoutDoc);
    if (matches.Count > 0)
    {
        string finalLogout = string.Format("http://m.facebook.com/logout{0}", 
            matches[0].Groups[1].ToString().Replace("amp;", "")); 
         webBrowser1.Navigate(new Uri(finalLogout));
    }
}