Xamarin

Callback URLs are the URLs that Auth0 invokes after the authentication process. Auth0 routes your application back to this URL and appends additional parameters to it, including an access code which will be exchanged for an ID Token, Access Token, and Refresh Token.

Since callback URLs can be manipulated, you will need to add your application's URL to your application's Allowed Callback URLs for security. This will enable Auth0 to recognize these URLs as valid. If omitted, authentication will not be successful.

• For Android, the callback URL will be in the format

  YOUR_ANDROID_PACKAGE_NAME://{yourDomain}/android/YOUR_ANDROID_PACKAGE_NAME/callback

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  where YOUR_ANDROID_PACKAGE_NAME is the Package Name for your application, such as com.mycompany.myapplication.

• For iOS, the callback URL will be in the format

  YOUR_BUNDLE_IDENTIFIER://{yourDomain}/ios/YOUR_BUNDLE_IDENTIFIER/callback

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  where YOUR_BUNDLE_IDENTIFIER is the Bundle Identifier for your application, such as com.mycompany.myapplication.

Ensure that the Callback URL is in lowercase.

Install-Package Auth0.OidcClient.AndroidX

Install-Package Auth0.OidcClient.iOS

To integrate Auth0 login into your application, instantiate an instance of the Auth0Client class, configuring the Auth0 Domain and Client ID:

using Auth0.OidcClient;

var client = new Auth0Client(new Auth0ClientOptions
{
    Domain = "{yourDomain}",
    ClientId = "{yourClientId}"
}, this);

Then, call the LoginAsync method which will redirect the user to the login screen. You will typically do this in the event handler for a UI control such as a Login button.

var loginResult = await client.LoginAsync();

After a user has logged in, they will be redirected back to your application at the Callback URL that was registered before. In both Android and iOS you need to handle this callback to complete the authentication flow.

Register an intent which will handle this callback URL. An easy way to do this is to register the intent on the same activity from which you called the LoginAsync method to initiate the authentication flow.

[Activity(Label = "AndroidSample", MainLauncher = true, Icon = "@drawable/icon",
    LaunchMode = LaunchMode.SingleTask)]
[IntentFilter(
    new[] { Intent.ActionView },
    Categories = new[] { Intent.CategoryDefault, Intent.CategoryBrowsable },
    DataScheme = "YOUR_ANDROID_PACKAGE_NAME",
    DataHost = "{yourDomain}",
    DataPathPrefix = "/android/YOUR_ANDROID_PACKAGE_NAME/callback")]
public class MainActivity : Activity
{
    // Code omitted
}

Replace YOUR_ANDROID_PACKAGE_NAME in the code sample above with the actual Package Name for your application, such as com.mycompany.myapplication. Also ensure that all the text for the DataScheme, DataHost, and DataPathPrefix is in lower case. Also, set LaunchMode = LaunchMode.SingleTask for the Activity, otherwise the system will create a new instance of the activity every time the Callback URL gets called.

Now write code to handle the intent. You can do this by overriding the OnNewIntent method. Inside the method you need to call the Send method on the ActivityMediator to complete the authentication cycle:

protected override async void OnNewIntent(Intent intent)
{
    base.OnNewIntent(intent);

    Auth0.OidcClient.ActivityMediator.Instance.Send(intent.DataString);
}

Register the URL scheme for your Callback URL which your application should handle:

1. Open your application's Info.plist file in Visual Studio for Mac, and go to the Advanced tab.
2. Under URL Types, click the Add URL Type button
3. Set the Identifier as Auth0, the URL Schemes the same as your application's Bundle Identifier, and the Role as None

This is an example of the XML representation of your info.plist file after you have added the URL Type:

<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleTypeRole</key>
        <string>None</string>
        <key>CFBundleURLName</key>
        <string>Auth0</string>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>YOUR_BUNDLE_IDENTIFIER</string>
        </array>
    </dict>
</array>

You need to handle the Callback URL in the OpenUrl event in your AppDelegate class. You need to notify the Auth0 OIDC Client to finish the authentication flow by calling the Send method of the ActivityMediator singleton, pass along the URL that was sent in:

using Auth0.OidcClient;

[Register("AppDelegate")]
public class AppDelegate : UIApplicationDelegate
{
    public override bool OpenUrl(UIApplication application, NSUrl url, string sourceApplication, NSObject annotation)
    {
        ActivityMediator.Instance.Send(url.AbsoluteString);

        return true;
    }
}

With the above code in place, a user can log in to your application using Auth0.

The returned login result will indicate whether authentication was successful and if so contain the tokens and claims of the user.

You can check the IsError property of the result to see whether the login has failed. The ErrorMessage will contain more information regarding the error which occurred.

var loginResult = await client.LoginAsync();

if (loginResult.IsError)
{
    Debug.WriteLine($"An error occurred during login: {loginResult.Error}")
}

On successful login, the login result will contain the ID Token and Access Token in the IdentityToken and AccessToken properties respectively.

var loginResult = await client.LoginAsync();

if (!loginResult.IsError)
{
    Debug.WriteLine($"id_token: {loginResult.IdentityToken}");
    Debug.WriteLine($"access_token: {loginResult.AccessToken}");
}

On successful login, the login result will contain the user information in the User property, which is a ClaimsPrincipal.

To obtain information about the user, you can query the claims. You can, for example, obtain the user's name and email address from the name and email claims:

if (!loginResult.IsError)
{
    Debug.WriteLine($"name: {loginResult.User.FindFirst(c => c.Type == "name")?.Value}");
    Debug.WriteLine($"email: {loginResult.User.FindFirst(c => c.Type == "email")?.Value}");
}

You can obtain a list of all the claims contained in the ID Token by iterating through the Claims collection:

if (!loginResult.IsError)
{
    foreach (var claim in loginResult.User.Claims)
    {
        Debug.WriteLine($"{claim.Type} = {claim.Value}");
    }
}

To log the user out call the LogoutAsync method.

BrowserResultType browserResult = await client.LogoutAsync();