Xamarin.Auth: Using Facebook oauth, how to redirect to my app? - facebook

Question

I've just started using Xamarin.Auth and I want to enable Facebook login via oauth.
Here is my config:
public static string ClientId = "client id";
public static string ClientSecret = "client secret";
public static string Scope = "email";
public static string AuthorizeUrl = "https://m.facebook.com/dialog/oauth";
public static string RedirectUrl = "https://www.facebook.com/connect/login_success.html";
public static string AccessTokenUrl = "https://m.facebook.com/dialog/oauth/token";
Code for initiating the authentication:
public class AuthenticationPageRenderer : PageRenderer
{
public override void ViewDidAppear(bool animated)
{
base.ViewDidAppear (animated);
var auth = new OAuth2Authenticator (
Constants.ClientId,
Constants.ClientSecret,
Constants.Scope,
new Uri (Constants.AuthorizeUrl),
new Uri (Constants.RedirectUrl),
new Uri (Constants.AccessTokenUrl)
);
auth.Completed += OnAuthenticationCompleted;
PresentViewController (auth.GetUI (), true, null);
}
async void OnAuthenticationCompleted (object sender, AuthenticatorCompletedEventArgs e)
{
Debug.WriteLine ("AUTH Completed!");
if (e.IsAuthenticated) {
}
}
}
Seems to work fine, but instead of redirecting the user to https://www.facebook.com/connect/login_success.html, I want to redirect him back to my app again. Any help much appreciated!
Best,
Sascha

Answer 1

You can "redirect back" to your app again by simply invoking your own method to display the app's page you want to show to your user like this.
async void OnAuthenticationCompleted (object sender, AuthenticatorCompletedEventArgs e)
{
Debug.WriteLine ("AUTH Completed!");
if (e.IsAuthenticated) {
//invoke the method that display the app's page
//that you want to present to user
App.SuccessfulLoginAction.Invoke();
}
}
In your App.cs
public static Action SuccessfulLoginAction
{
get
{
return new Action(() =>
{
//show your app page
var masterDetailPage = Application.Current.MainPage as MasterDetailPage;
masterDetailPage.Detail = new NavigationPage((Page)Activator.CreateInstance(typeof(MainPage)));
masterDetailPage.IsPresented = false;
});
}
}
Assuming that MainPage is the page you wanted to show after successful login. I am using Xamarin.Forms with MasterDetailPage to display pages in my example which maybe different from your app but the concept is the same.

Answer 2

Just call DismissViewController (true, null) in your OnAuthenticationCompleted method. Or use the async equivalent:
async void OnAuthenticationCompleted(object sender, AuthenticatorCompletedEventArgs e)
{
Debug.WriteLine("AUTH Completed!");
await DismissViewControllerAsync(true);
if (e.IsAuthenticated)
{
}
}