Sign In with Apple跨设备报错No Credential Available的问题求助

错误原因 #

这个报错来自ASAuthorizationPasswordProvider的请求，该请求用于读取设备钥匙串中已保存的Apple登录凭证。其他设备未保存对应账号的密码凭证时，该请求会失败；而你的代码同时发起了Apple ID授权和密码凭证请求，系统可能优先处理密码请求，失败后直接返回错误，未触发Apple ID登录界面。

修复步骤及代码修改 #

1. 拆分请求逻辑，优先处理密码凭证，失败后发起Apple ID授权 #

修改按钮点击方法，先尝试钥匙串密码凭证登录，失败后再触发Apple ID授权流程：

@objc private func appleSignInPressed() {
    // 先尝试钥匙串中的密码凭证登录
    let passwordProvider = ASAuthorizationPasswordProvider()
    let passwordRequest = passwordProvider.createRequest()
    let passwordController = ASAuthorizationController(authorizationRequests: [passwordRequest])
    passwordController.delegate = self
    passwordController.presentationContextProvider = self
    passwordController.performRequests()
}

2. 优化错误代理，处理凭证不存在的情况 #

在错误代理中判断错误码，当遇到credentialsNotFound时，自动发起Apple ID授权：

extension WelcomeViewController: ASAuthorizationControllerDelegate {
    func authorizationController(controller: ASAuthorizationController, didCompleteWithAuthorization authorization: ASAuthorization) {
        switch authorization.credential {
        case let passwordCredential as ASPasswordCredential:
            // 钥匙串凭证登录成功
            let username = passwordCredential.user
            let password = passwordCredential.password
            viewModel.didTouchLoginButton(with: username, and: password, feeds: [], referralLink: nil)
        case let credentials as ASAuthorizationAppleIDCredential:
            // Apple ID授权成功
            let givenName = credentials.fullName?.givenName ?? "user"
            // 仅首次授权时会返回email，后续授权需从服务器或本地存储获取
            if let email = credentials.email {
                print("\(givenName) \(email)")
                // 保存userID用于后续状态检查
                UserDefaults.standard.set(credentials.user, forKey: "AppleUserID")
            } else {
                // 非首次授权，用userID去服务器获取用户信息
                viewModel.didAppleSignIn(withUserID: credentials.user)
            }
        default:
            startSignUpFlow()
        }
    }
    
    func authorizationController(controller: ASAuthorizationController, didCompleteWithError error: Error) {
        guard let authError = error as? ASAuthorizationError else {
            print("FAILED: \(error.localizedDescription)")
            return
        }
        
        switch authError.code {
        case .canceled:
            // 用户取消操作，无需处理
            break
        case .credentialsNotFound:
            // 钥匙串无凭证，发起Apple ID授权请求
            let appleIDProvider = ASAuthorizationAppleIDProvider()
            let appleIDRequest = appleIDProvider.createRequest()
            appleIDRequest.requestedScopes = [.email, .fullName]
            
            let appleIDController = ASAuthorizationController(authorizationRequests: [appleIDRequest])
            appleIDController.delegate = self
            appleIDController.presentationContextProvider = self
            appleIDController.performRequests()
        default:
            print("FAILED: \(authError.localizedDescription)")
        }
    }
}

3. 确保展示上下文实现正确 #

添加ASAuthorizationControllerPresentationContextProviding扩展，返回正确的窗口用于展示登录弹窗：

extension WelcomeViewController: ASAuthorizationControllerPresentationContextProviding {
    func presentationAnchor(for controller: ASAuthorizationController) -> ASPresentationAnchor {
        // 返回当前控制器所在的窗口，适配iOS 13+场景
        return view.window ?? UIWindow(frame: UIScreen.main.bounds)
    }
}

4. 处理已授权用户的自动登录 #

在控制器加载时，检查已保存的Apple用户ID的凭证状态，实现自动登录：

override func viewDidLoad() {
    super.viewDidLoad()
    
    let appleIDProvider = ASAuthorizationAppleIDProvider()
    if let userID = UserDefaults.standard.string(forKey: "AppleUserID") {
        appleIDProvider.getCredentialState(forUserID: userID) { [weak self] state, error in
            DispatchQueue.main.async {
                guard let self = self else { return }
                switch state {
                case .authorized:
                    // 用户已授权，直接发起登录请求
                    self.viewModel.didAppleSignIn(withUserID: userID)
                case .revoked, .notFound:
                    // 凭证已失效或未找到，清除本地存储
                    UserDefaults.standard.removeObject(forKey: "AppleUserID")
                default:
                    break
                }
            }
        }
    }
}

额外注意事项 #

• 仅用户首次授权时，ASAuthorizationAppleIDCredential会返回email和fullName；后续授权需通过保存的userID从服务器获取用户信息。
• 确保你的App已在Apple开发者后台配置好Sign In with Apple功能，且Bundle ID匹配。

内容的提问来源于stack exchange，提问作者tHatpart