在 Xamarin.iOS 中使用 Apple 登录

项目
04/19/2024

使用 Apple 登录是一项新服务，为第三方身份验证服务的用户提供标识保护。从 iOS 13 开始，Apple 要求使用第三方身份验证服务的任何新应用也应提供 Apple 登录。在 2020 年 4 月之前，更新的现有应用无需添加 Apple 登录。

本文档介绍了如何将使用 Apple 登录添加到 iOS 13 应用程序。

Apple 开发人员设置

在使用 Apple 登录生成和运行应用之前，需要完成这些步骤。在 Apple 开发人员证书、标识符和配置文件门户上：

创建新的应用 ID 标识符。
在“说明”字段中设置说明。
选择显式捆绑 ID 并在字段中设置 com.xamarin.AddingTheSignInWithAppleFlowToYourApp。
启用“使用 Apple 登录”功能并注册新标识。
使用新的标识创建新的预配配置文件。
在设备上下载并安装它。
在 Visual Studio 中，在 Entitlements.plist 文件中启用使用 Apple 登录功能。

应用启动时，或首次需要检查用户的身份验证状态时，实例化 ASAuthorizationAppleIdProvider 并检查当前状态：

var appleIdProvider = new ASAuthorizationAppleIdProvider ();
appleIdProvider.GetCredentialState (KeychainItem.CurrentUserIdentifier, (credentialState, error) => {
    switch (credentialState) {
    case ASAuthorizationAppleIdProviderCredentialState.Authorized:
        // The Apple ID credential is valid.
        break;
    case ASAuthorizationAppleIdProviderCredentialState.Revoked:
        // The Apple ID credential is revoked.
        break;
    case ASAuthorizationAppleIdProviderCredentialState.NotFound:
        // No credential was found, so show the sign-in UI.
        InvokeOnMainThread (() => {
            var storyboard = UIStoryboard.FromName ("Main", null);

            if (!(storyboard.InstantiateViewController (nameof (LoginViewController)) is LoginViewController viewController))
                return;

            viewController.ModalPresentationStyle = UIModalPresentationStyle.FormSheet;
            viewController.ModalInPresentation = true;
            Window?.RootViewController?.PresentViewController (viewController, true, null);
        });
        break;
    }
});

在此代码中，在 AppDelegate.cs 的 FinishedLaunching期间调用，应用将在状态 NotFound 时处理，并将 LoginViewController 呈现给用户。如果状态已返回 Authorized 或 Revoked，则可能会向用户显示其他操作。

实现登录逻辑并提供使用 Apple 登录的 UIViewController 需要实现 IASAuthorizationControllerDelegate 和 IASAuthorizationControllerPresentationContextProviding，如以下示例中的 LoginViewController 所示。

public partial class LoginViewController : UIViewController, IASAuthorizationControllerDelegate, IASAuthorizationControllerPresentationContextProviding {
    public LoginViewController (IntPtr handle) : base (handle)
    {
    }

    public override void ViewDidLoad ()
    {
        base.ViewDidLoad ();
        // Perform any additional setup after loading the view, typically from a nib.

        SetupProviderLoginView ();
    }

    public override void ViewDidAppear (bool animated)
    {
        base.ViewDidAppear (animated);

        PerformExistingAccountSetupFlows ();
    }

    void SetupProviderLoginView ()
    {
        var authorizationButton = new ASAuthorizationAppleIdButton (ASAuthorizationAppleIdButtonType.Default, ASAuthorizationAppleIdButtonStyle.White);
        authorizationButton.TouchUpInside += HandleAuthorizationAppleIDButtonPress;
        loginProviderStackView.AddArrangedSubview (authorizationButton);
    }

    // Prompts the user if an existing iCloud Keychain credential or Apple ID credential is found.
    void PerformExistingAccountSetupFlows ()
    {
        // Prepare requests for both Apple ID and password providers.
        ASAuthorizationRequest [] requests = {
            new ASAuthorizationAppleIdProvider ().CreateRequest (),
            new ASAuthorizationPasswordProvider ().CreateRequest ()
        };

        // Create an authorization controller with the given requests.
        var authorizationController = new ASAuthorizationController (requests);
        authorizationController.Delegate = this;
        authorizationController.PresentationContextProvider = this;
        authorizationController.PerformRequests ();
    }

    private void HandleAuthorizationAppleIDButtonPress (object sender, EventArgs e)
    {
        var appleIdProvider = new ASAuthorizationAppleIdProvider ();
        var request = appleIdProvider.CreateRequest ();
        request.RequestedScopes = new [] { ASAuthorizationScope.Email, ASAuthorizationScope.FullName };

        var authorizationController = new ASAuthorizationController (new [] { request });
        authorizationController.Delegate = this;
        authorizationController.PresentationContextProvider = this;
        authorizationController.PerformRequests ();
    }
}

Animation of sample app using Sign In with Apple

此示例代码检查 PerformExistingAccountSetupFlows 中的当前登录状态，并作为委托连接到当前视图。如果找到现有的 iCloud 密钥链凭据或 Apple ID 凭据，系统会提示用户使用该凭据。

Apple 提供 ASAuthorizationAppleIdButton，这是一个专门用于此目的的按钮。触摸时，该按钮将触发方法 HandleAuthorizationAppleIDButtonPress 中处理的工作流。

处理授权

在 IASAuthorizationController 实现任何自定义逻辑来存储用户帐户。以下示例将用户帐户存储在 Apple 自己的存储服务 Keychain 中。

#region IASAuthorizationController Delegate

[Export ("authorizationController:didCompleteWithAuthorization:")]
public void DidComplete (ASAuthorizationController controller, ASAuthorization authorization)
{
    if (authorization.GetCredential<ASAuthorizationAppleIdCredential> () is ASAuthorizationAppleIdCredential appleIdCredential) {
        var userIdentifier = appleIdCredential.User;
        var fullName = appleIdCredential.FullName;
        var email = appleIdCredential.Email;

        // Create an account in your system.
        // For the purpose of this demo app, store the userIdentifier in the keychain.
        try {
            new KeychainItem ("com.example.apple-samplecode.juice", "userIdentifier").SaveItem (userIdentifier);
        } catch (Exception) {
            Console.WriteLine ("Unable to save userIdentifier to keychain.");
        }

        // For the purpose of this demo app, show the Apple ID credential information in the ResultViewController.
        if (!(PresentingViewController is ResultViewController viewController))
            return;

        InvokeOnMainThread (() => {
            viewController.UserIdentifierText = userIdentifier;
            viewController.GivenNameText = fullName?.GivenName ?? "";
            viewController.FamilyNameText = fullName?.FamilyName ?? "";
            viewController.EmailText = email ?? "";

            DismissViewController (true, null);
        });
    } else if (authorization.GetCredential<ASPasswordCredential> () is ASPasswordCredential passwordCredential) {
        // Sign in using an existing iCloud Keychain credential.
        var username = passwordCredential.User;
        var password = passwordCredential.Password;

        // For the purpose of this demo app, show the password credential as an alert.
        InvokeOnMainThread (() => {
            var message = $"The app has received your selected credential from the keychain. \n\n Username: {username}\n Password: {password}";
            var alertController = UIAlertController.Create ("Keychain Credential Received", message, UIAlertControllerStyle.Alert);
            alertController.AddAction (UIAlertAction.Create ("Dismiss", UIAlertActionStyle.Cancel, null));

            PresentViewController (alertController, true, null);
        });
    }
}

[Export ("authorizationController:didCompleteWithError:")]
public void DidComplete (ASAuthorizationController controller, NSError error)
{
    Console.WriteLine (error);
}

#endregion

授权控制器

此实现的最后一部分是管理提供程序的授权请求的 ASAuthorizationController。

#region IASAuthorizationControllerPresentation Context Providing

public UIWindow GetPresentationAnchor (ASAuthorizationController controller) => View.Window;

#endregion

Apple 开发人员设置

检查登录状态

使用 Apple 登录的 LoginViewController

处理授权

授权控制器

相关链接

其他资源