Monitor FirebaseAuth login status with TCA

FirebaseAuthClient.swift

import ComposableArchitecture
import FirebaseCore
import FirebaseAuth
import GoogleSignIn

struct FirebaseAuthClient {
    var observeSignInState: () async -> AsyncStream<Bool>
}

extension FirebaseAuthClient {
    static let liveValue = Self.live()

    static func live() -> Self {
        // To remove monitoring if called more than once.
        var stateChangeListener: AuthStateDidChangeListenerHandle?

        return Self(observeSignInState: {
            if let stateChangeListener {
                Auth.auth().removeStateDidChangeListener(stateChangeListener)
            }

            return AsyncStream(Bool.self) { continuation in
                stateChangeListener = Auth.auth().addStateDidChangeListener { auth, _ in
                    continuation.yield(auth.currentUser != nil)
                }
            }          
        }
    }
}
 
extension FirebaseAuthClient {
    public static let noop = Self(
        observeSignInState: { AsyncStream(Bool.self) { $0.finish() } }
    )
}

// MARK: - For Dependencies

enum FirebaseAuthClientKey: DependencyKey {
    static let liveValue = FirebaseAuthClient.liveValue
    static let previewValue = FirebaseAuthClient.noop
}

extension DependencyValues {
    var firebaseAuthClient: FirebaseAuthClient {
        get { self[FirebaseAuthClientKey.self] }
        set { self[FirebaseAuthClientKey.self] = newValue }
    }
}

Hi @andemengo . I am using this code from AppDelegate didFinishLaunching. isowords was used as a reference.
https://github.com/pointfreeco/isowords/blob/455238749625d8a84c23ee641d537971695416fc/App/iOS/App.swift#L39

That's perfect! Thanks also for the reference.

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Just to be helpful at line 27 it's missing a the closing parentheses ).