SwiftUI应用中Firebase Auth Revoke Token失效，如何启用Apple授权码流？

要解决你遇到的“Code flow is not enabled for Apple”错误，需要从Firebase控制台配置和客户端代码修改两方面启用授权码流，具体步骤如下：

一、Firebase控制台开启授权码流 #

• 打开Firebase控制台，进入你的项目的「Authentication」模块
• 切换到「登录方法」标签页，找到Apple登录选项并点击「编辑」
• 勾选「启用授权码流」，然后保存配置
• 若此前未完成Apple开发者后台配置，需先补充：在Apple Developer Portal创建对应服务ID，启用Sign In with Apple功能，将服务ID填入Firebase的Apple登录配置，并上传Apple生成的.p8私钥文件。

二、修改SwiftUI客户端的Apple登录代码 #

原来的Apple登录可能使用的是隐式流，现在需要调整为授权码流，核心是获取authorizationCode并传给Firebase：

1. 生成并存储nonce（用于身份验证，和之前的隐式流逻辑一致）：

private func randomNonceString(length: Int = 32) -> String {
    precondition(length > 0)
    let charset: [Character] =
        Array("0123456789ABCDEFGHIJKLMNOPQRSTUVXYZabcdefghijklmnopqrstuvwxyz-._")
    var result = ""
    var remainingLength = length
    
    while remainingLength > 0 {
        let randoms: [UInt8] = (0..<16).map { _ in
            var random: UInt8 = 0
            let errorCode = SecRandomCopyBytes(kSecRandomDefault, 1, &random)
            if errorCode != errSecSuccess {
                fatalError("无法生成随机数：SecRandomCopyBytes失败，错误码\(errorCode)")
            }
            return random
        }
        
        randoms.forEach { random in
            if remainingLength == 0 {
                return
            }
            
            if random < charset.count {
                result.append(charset[Int(random)])
                remainingLength -= 1
            }
        }
    }
    
    return result
}

2. 发起Apple登录请求时，明确触发授权码返回：

func startAppleSignIn() {
    let nonce = randomNonceString()
    self.currentNonce = nonce // 存储nonce，后续验证用
    
    let provider = ASAuthorizationAppleIDProvider()
    let request = provider.createRequest()
    request.requestedScopes = [.fullName, .email]
    // 关键：指定登录操作，让Apple返回授权码
    request.requestedOperation = .operationLogin
    
    let controller = ASAuthorizationController(authorizationRequests: [request])
    controller.delegate = self
    controller.presentationContextProvider = self
    controller.performRequests()
}

3. 在授权成功回调中，获取authorizationCode并传给Firebase：

func authorizationController(controller: ASAuthorizationController, didCompleteWithAuthorization authorization: ASAuthorization) {
    guard let appleIDCredential = authorization.credential as? ASAuthorizationAppleIDCredential else { return }
    
    // 提取身份令牌和授权码
    guard let identityToken = appleIDCredential.identityToken,
          let idTokenString = String(data: identityToken, encoding: .utf8),
          let authorizationCode = appleIDCredential.authorizationCode,
          let codeString = String(data: authorizationCode, encoding: .utf8),
          let nonce = currentNonce else {
        print("无法获取Apple登录所需的令牌或授权码")
        return
    }
    
    // 创建Firebase OAuth凭证，传入授权码
    let credential = OAuthProvider.credential(withProviderID: "apple.com",
                                              idToken: idTokenString,
                                              rawNonce: nonce,
                                              authorizationCode: codeString)
    
    // 登录Firebase
    Auth.auth().signIn(with: credential) { result, error in
        if let error = error {
            print("Firebase登录失败：\(error.localizedDescription)")
            return
        }
        // 登录成功后的业务逻辑，比如跳转主页
    }
}

三、调用revokeToken并删除账号 #

配置完成后，即可正常执行令牌撤销和账号删除逻辑：

func deleteUserAccount() {
    guard let currentUser = Auth.auth().currentUser else { return }
    
    Auth.auth().revokeToken { revokeError in
        if let revokeError = revokeError {
            print("撤销令牌失败：\(revokeError.localizedDescription)")
            return
        }
        
        // 令牌撤销成功，执行账号删除
        currentUser.delete { deleteError in
            if let deleteError = deleteError {
                print("删除账号失败：\(deleteError.localizedDescription)")
            } else {
                print("账号删除成功，用户已退出")
                // 处理退出后的UI逻辑，比如返回登录页
            }
        }
    }
}

四、关键注意事项 #

• 确保Apple开发者后台的服务ID与Firebase配置的完全一致，且已启用Sign In with Apple
• Firebase的Apple登录配置必须上传有效的.p8私钥，否则授权码流无法正常工作
• Xcode项目需已添加「Sign In with Apple」Capability
• 测试时请使用真实Apple账号，部分模拟器环境可能无法正常触发授权码流

内容的提问来源于stack exchange，提问作者Jeff G