将 Firebase 身份验证与新的 @App 协议一起使用

Question

我是 iOS 开发新手，正在努力使用 SwiftUI 中的新 @App 协议实现 Firebase 手机身份验证。 Firebase 的文档是为 UIKit 编写的，SwiftUI 的在线教程使用 AppDelegate 和 SceneDelegate 而不是 App 结构中的新 @main 协议。

我的具体问题如下：我将如何/在哪里注入我创建的这个身份验证状态类？

import Foundation
class AuthenticationState: NSObject,  ObservableObject
{
    @Published var loggedInUser: User?
    @Published var isAuthenticating = false
    @Published var error: NSError?
    
    static let shared = AuthenticationState();
    
    private let auth = Auth.auth();
    fileprivate var currentNonce: String?
    
    func login(with loginOption: LoginOption) {
            self.isAuthenticating = true
            self.error = nil

            switch loginOption {
                case .signInWithApple:
                    handleSignInWithApple()
            }
        }

        func signup(email: String, password: String, passwordConfirmation: String) {
            // TODO
        }

       private func handleSignInWithApple() {
            // TODO
        }
}
    

其次，AuthenticationState 类不知道 Firebase Auth 对象，我认为是因为它配置不正确。到目前为止，我在 AppDelegate 类中配置 Firebase：

import UIKit
import Firebase


class AppDelegate: UIResponder, UIApplicationDelegate {

  var window: UIWindow?

  func application(_ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions:
        [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    FirebaseApp.configure()
    
    
    return true
  }
    
            
    
   
    }

然而，我还有一个 MapworkApp.swift 文件，我认为它应该替换 AppDelegate，但我不确定：

import SwiftUI
import Firebase
@main
struct MapworkApp: App {
    let persistenceController = PersistenceController.shared
    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environment(\.managedObjectContext, persistenceController.container.viewContext)
        }
    }
}

struct MapworkApp_Previews: PreviewProvider {
    static var previews: some View {
        /*@START_MENU_TOKEN@*/Text("Hello, World!")/*@END_MENU_TOKEN@*/
    }
}

我目前收到的运行时错误：

020-12-16 13:22:34.416917-0700 Mapwork[1351:332863] 7.3.0 - [Firebase/Core][I-COR000003] The default Firebase app has not yet been configured. Add `[FIRApp configure];` (`FirebaseApp.configure()` in Swift) to your application initialization. Read more: 
2020-12-16 13:22:34.417240-0700 Mapwork[1351:332633] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'The default FIRApp instance must be configured before the default FIRAuthinstance can be initialized. One way to ensure that is to call `[FIRApp configure];` (`FirebaseApp.configure()` in Swift) in the App Delegate's `application:didFinishLaunchingWithOptions:` (`application(_:didFinishLaunchingWithOptions:)` in Swift).'
*** First throw call stack:
(0x1863a586c 0x19b314c50 0x18629e4a4 0x102bc8918 0x1028465d8 0x1028466f4 0x102845c1c 0x102845be4 0x102ec96c0 0x102ecb1f8 0x18a32c5bc 0x102845c64 0x102854aa0 0x102854cbc 0x18cdba724 0x102854c18 0x102855028 0x185fda6b0)
libc++abi.dylib: terminating with uncaught exception of type NSException
terminating with uncaught exception of type NSException
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'The default FIRApp instance must be configured before the default FIRAuthinstance can be initialized. One way to ensure that is to call `[FIRApp configure];` (`FirebaseApp.configure()` in Swift) in the App Delegate's `application:didFinishLaunchingWithOptions:` (`application(_:didFinishLaunchingWithOptions:)` in Swift).'
Message from debugger: The LLDB RPC server has exited unexpectedly. Please file a bug if you have reproducible steps.

任何帮助或指导将不胜感激，因为在线文档现在不适用。

Answer 1

对于许多 Firebase API，您不需要使用 AppDelegate 方法。相反，您可以在应用的初始化程序中初始化 Firebase，如下所示：

import SwiftUI
import Firebase

@main
struct MapworkApp: App {
  init() {
    FirebaseApp.configure()
  }
  var body: some Scene {
    WindowGroup {
      ContentView()
    }
  }
}

这适用于使用 Cloud Firestore 和 Firebase 身份验证（通过 Apple 登录）的应用。

对于某些 Firebase 的 SDK，您需要实现 AppDelegate。为此，请像这样实现您的AppDelegate：

class AppDelegate: NSObject, UIApplicationDelegate {
  func application(_ application: UIApplication,
                   didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
    print("Application is starting up. ApplicationDelegate didFinishLaunchingWithOptions.")
    return true
  }
  
  // ... add any callbacks your app might require
}

然后，将您的 App 连接到 AppDelegate，如下所示：

@main
struct MapworkApp: App {
  @UIApplicationDelegateAdaptor(AppDelegate.self) var delegate
  
  init() {
    FirebaseApp.configure()
  }
  
  var body: some Scene {
    WindowGroup {
      ContentView()
    }
  }
}

您可能必须将呼叫FirebaseApp.configure() 转移到AppDelegate。在这种情况下，您的 AppDelegate 和 App 可能如下所示（如果您愿意，可以将它们保存在同一个文件中）：

class AppDelegate: UIResponder, UIApplicationDelegate {

  func application(_ application: UIApplication,
                   didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

    FirebaseApp.configure()

    return true
  }
}

@main
struct MapworkApp: App {
  @UIApplicationDelegateAdaptor(AppDelegate.self) var delegate
  
  var body: some Scene {
    WindowGroup {
      ContentView()
    }
  }
}

要了解更多信息，请查看我关于新应用程序生命周期的文章：

• Firebase and the new SwiftUI 2 Application Life Cycle - SwiftUI 2
• The Ultimate Guide to the SwiftUI 2 Application Life Cycle - SwiftUI 2

我编写的这个示例应用程序展示了如何使用 SwiftUI 和 Firebase 构建一个简单的待办事项列表应用程序：peterfriese/MakeItSo。最新版本的代码遵循新的 SwiftUI 2 应用程序生命周期，并包括 Sign in with Apple。