Firebase 会话变量始终为零答案

【问题标题】：Firebase session variable is always nilFirebase 会话变量始终为零
【发布时间】：2021-02-27 02:17:38
【问题描述】：

应用程序架构很简单：如果会话变量为零，则会出现登录屏幕。如果成功输入密码和登录名，我们将创建一个新的用户模型，并且会话变量不再为 nil。但是，这并没有发生，因此无论登录是否成功，登录屏幕总是出现在我们面前。

（我在打开应用程序“Got user: ”时收到一条调试消息，表明身份验证没有问题）

ContentView.swift：

import SwiftUI

struct ContentView: View {
    @EnvironmentObject var session: SessionStore
    
    func getUser () {
          session.listen()
      }

    var body: some View {
        Group {
            if (session.session != nil) {
                Text("Hello user!")
              } else {
                SignInView()
              }
        }.onAppear(perform: getUser)
    }
}

SessionStore.swift：

import SwiftUI
import Firebase
import Combine

class SessionStore : ObservableObject {
    var didChange = PassthroughSubject<SessionStore, Never>()
    var session: User? { didSet { self.didChange.send(self) }}
    var handle: AuthStateDidChangeListenerHandle?

    func listen () {
        // monitor authentication changes using firebase
        handle = Auth.auth().addStateDidChangeListener { (auth, user) in
            if let user = user {
                // if we have a user, create a new user model
                print("Got user: \(user)")
                self.session = User(
                    uid: user.uid,
                    displayName: user.displayName,
                    email: user.email
                    
                )
            } else {
                // if we don't have a user, set our session to nil
                self.session = nil
            }
        }
    }

    func signUp(
            email: String,
            password: String,
            handler: @escaping AuthDataResultCallback
            ) {
            Auth.auth().createUser(withEmail: email, password: password, completion: handler)
        }

    func signIn(
        email: String,
        password: String,
        handler: @escaping AuthDataResultCallback
        ) {
        Auth.auth().signIn(withEmail: email, password: password, completion: handler)
    }

    func signOut () -> Bool {
        do {
            try Auth.auth().signOut()
            self.session = nil
            return true
        } catch {
            return false
        }
    }
}

SignInView.swift：

import SwiftUI

struct SignInView : View {

    @State var email: String = ""
    @State var password: String = ""
    @State var loading = false
    @State var error = false

    @EnvironmentObject var session: SessionStore

    func signIn () {
        loading = true
        error = false
        session.signIn(email: email, password: password) { (result, error) in
            self.loading = false
            if error != nil {
                self.error = true
            } else {
                self.email = ""
                self.password = ""
            }
        }
    }

    var body: some View {
        VStack {
            TextField("email address", text: $email)
            SecureField("password", text: $password)
            if (error) {
                Text("ahhh crap")
            }
            Button(action: signIn) {
                Text("Sign In")
            }
        }
    }
}

【问题讨论】：

标签： ios swift firebase firebase-authentication swiftui

【解决方案1】：

要让视图观察到属性，您需要将其发布，而不是使用自定义发布者，例如

class SessionStore : ObservableObject {
    @Published var session: User? = nil    // << here !!

// ... other code

最好在主队列上明确分配已发布的属性，例如

 DispatchQueue.main.async {
    self.session = User(
        uid: user.uid,
        displayName: user.displayName,
        email: user.email
    )
 }

【讨论】：