在 iOS 上退出应用后保持 Firebase 身份验证状态

Question

我正在使用以下类来处理用户的身份验证状态和登录：

class AuthenticationState: NSObject, ObservableObject {

     // MARK: Properties
    let db = Firestore.firestore()

    @Published var loggedInUser: FirebaseAuth.User?
    @Published var isAuthenticating = false
    @Published var error: NSError?

    static let shared = AuthenticationState()

    private let authState = Auth.auth()
    fileprivate var currentNonce: String?

    // MARK: Methods
    func login(with loginOption: LoginOption) {
        self.isAuthenticating = true
        self.error = nil

        switch loginOption {
            case .signInWithApple:
                handleSignInWithApple()

            case let .emailAndPassword(email, password):
                handleSignInWith(email: email, password: password)
        }
    }

    private func handleSignInWith(email: String, password: String) {
        authState.signIn(withEmail: email, password: password, completion: handleAuthResultCompletion)
    }

    func signup(email: String, password: String, passwordConfirmation: String) {
        guard password == passwordConfirmation else {
            self.error = NSError(domain: "", code: 9210, userInfo: [NSLocalizedDescriptionKey: "Password and confirmation does not match"])
            return
        }

        self.isAuthenticating = true
        self.error = nil

        authState.createUser(withEmail: email, password: password, completion: handleAuthResultCompletion)
    }

    private func handleAuthResultCompletion(auth: AuthDataResult?, error: Error?) {
        DispatchQueue.main.async {
        self.isAuthenticating = false
            if let user = auth?.user {
                self.loggedInUser = user
            } else if let error = error {
                self.error = error as NSError
            }
        }
    }

    func signout() {
        try? authState.signOut()
        self.loggedInUser = nil
    }
}

// Extension Below that handles sign in with apple, etc. 

这对于处理各种登录方法非常有效，但是当用户退出应用程序时，登录状态不再存在。退出应用程序后保持用户登录的最佳方式是什么？

Answer 1

Firebase 身份验证会自动将用户的身份验证状态保存到其钥匙串中，并在应用重新启动时尝试恢复该状态。

要恢复身份验证状态，它需要与服务器重新检查凭据，这可能需要一些时间。这就是您需要使用身份验证状态侦听器来获取此恢复状态的原因，如getting the currently signed in user 上的文档所示：

handle = Auth.auth().addStateDidChangeListener { (auth, user) in
  // ...
}

Answer 2

您可以通过多种方式做您想做的事。保存您的数据，任何类型的数据 - 在您的本地存储中由您决定，例如：

1. 默认值
2. 钥匙扣
3. 核心数据
4. 等等……

或者，在我看来，您可以尝试检查currentUser，如下所示：

let user = Auth.auth().currentUser

文档：https://firebase.google.com/docs/auth/ios/manage-users

对于 javascript：（身份验证状态持久性 )https://firebase.google.com/docs/auth/web/auth-state-persistence