Fiche 11.02

Fiche 11.02 — Firebase Auth en pratique

Objectif

Créer un service Firebase Auth utilisable dans une architecture SwiftUI / MVVM.

1. Service Auth

Swift

import FirebaseAuth

protocol AuthServiceProtocol {
    var currentUserId: String? { get }
    func signIn(email: String, password: String) async throws
    func register(email: String, password: String) async throws
    func logout() throws
    func deleteAccount() async throws
}

final class FirebaseAuthService: AuthServiceProtocol {
    var currentUserId: String? {
        Auth.auth().currentUser?.uid
    }
    
    func signIn(email: String, password: String) async throws {
        try await Auth.auth().signIn(withEmail: email, password: password)
    }
    
    func register(email: String, password: String) async throws {
        try await Auth.auth().createUser(withEmail: email, password: password)
    }
    
    func logout() throws {
        try Auth.auth().signOut()
    }
    
    func deleteAccount() async throws {
        guard let user = Auth.auth().currentUser else { return }
        try await user.delete()
    }
}

Le protocole rend le service testable.

2. LoginViewModel

Swift

@MainActor
final class FirebaseLoginViewModel: ObservableObject {
    @Published var email = ""
    @Published var password = ""
    @Published var isLoading = false
    @Published var errorMessage: String?
    
    private let authService: AuthServiceProtocol
    
    init(authService: AuthServiceProtocol = FirebaseAuthService()) {
        self.authService = authService
    }
    
    var isFormValid: Bool {
        email.contains("@") && password.count >= 8
    }
    
    func login() async {
        guard isFormValid else { return }
        
        isLoading = true
        errorMessage = nil
        
        do {
            try await authService.signIn(email: email, password: password)
        } catch {
            errorMessage = "Email ou mot de passe incorrect."
        }
        
        isLoading = false
    }
}

3. AuthState Firebase

Swift

@MainActor
final class FirebaseAuthState: ObservableObject {
    @Published var user: User?
    @Published var isLoading = true
    
    private var listener: AuthStateDidChangeListenerHandle?
    
    func start() {
        listener = Auth.auth().addStateDidChangeListener { [weak self] _, user in
            self?.user = user
            self?.isLoading = false
        }
    }
    
    func stop() {
        if let listener {
            Auth.auth().removeStateDidChangeListener(listener)
        }
    }
}

4. AppRootView

Swift

struct AppRootView: View {
    @StateObject private var authState = FirebaseAuthState()
    
    var body: some View {
        Group {
            if authState.isLoading {
                ProgressView()
            } else if authState.user == nil {
                LoginView()
            } else {
                MainTabView()
            }
        }
        .task {
            authState.start()
        }
    }
}

5. Logout depuis les réglages

Swift

struct SettingsView: View {
    private let authService = FirebaseAuthService()
    
    var body: some View {
        Button("Se déconnecter", role: .destructive) {
            try? authService.logout()
        }
    }
}

Le listener Firebase mettra automatiquement l’utilisateur à nil.

Points à connaître

Firebase Auth garde généralement l’utilisateur connecté automatiquement.

Pour tester proprement un ViewModel, il faut passer par un protocole et injecter un mock.

Résumé

Firebase Auth peut être encapsulé dans un service.
Le service doit avoir un protocole pour les tests.
Le ViewModel gère loading, erreur et validation.
La session globale se gère avec un listener Firebase.
Le logout déclenche automatiquement la mise à jour de session.