Sign in with Apple Supabase

LoginView.swift

import SwiftUI
import AuthenticationServices
import Supabase

struct LoginView: View {
    @State private var isSignedIn = false
    @State private var signInError: Error?
    
    @AppStorage("name") var currentUserName: String?
    @AppStorage("userID") var signedInUserId: String?
    @AppStorage("is_signed_in") var isUserSignedIn: Bool = false
    
    let supabase = SupabaseClient(supabaseURL: URL(string: "YOUR_PROJECT_URL")!, supabaseKey:
    "YOUR_PUBLIC_KEY")


    var body: some View {
        VStack(spacing: 40) {
            Spacer()
            
            // Logo
            Image(systemName: "YOUR_LOGO")
                .resizable()
                .scaledToFit()
                .frame(width: 150, height: 150)
            
            // Title
            Text("YOUR_APP_NAME")
                .font(.largeTitle)
                .fontWeight(.semibold)
            
            Spacer()
            
            SignInWithAppleButton(.signIn) { request in
                request.requestedScopes = [.fullName, .email]
            } onCompletion: { result in
                switch result {
                case .success(let authResults):
                    print("Authorization successful")
                    handleSignInWithApple(authorization: authResults)
                case .failure(let error):
                    print("Authorization failed: \(error.localizedDescription)")
                    signInError = error
                }
            }
            .frame(height: 55)
            .padding()
        }
        .padding(40)
        .multilineTextAlignment(.center)
        .alert(isPresented: Binding<Bool>.constant(signInError != nil)) {
            Alert(title: Text("Sign In Error"), message: Text(signInError?.localizedDescription ?? "Unknown error"), dismissButton: .default(Text("OK")))
        }
    }
    
    func handleSignInWithApple(authorization: ASAuthorization) {
        guard let appleIDCredential = authorization.credential as? ASAuthorizationAppleIDCredential else {
            print("Unable to fetch Apple ID Credential")
            return
        }
        
        guard let identityToken = appleIDCredential.identityToken,
              let tokenString = String(data: identityToken, encoding: .utf8) else {
            print("Unable to fetch identity token")
            return
        }
        
        Task {
            do {
                let session = try await supabase.auth.signInWithIdToken(credentials: .init(provider: .apple, idToken: tokenString))
                
                DispatchQueue.main.async {
                    self.currentUserName = appleIDCredential.fullName?.givenName
                    self.signedInUserId = session.user.id.uuidString
                    self.isUserSignedIn = true
                    self.isSignedIn = true
                }
            } catch {
                print("Error signing in with Supabase: \(error)")
                DispatchQueue.main.async {
                    self.signInError = error
                }
            }
        }
    }
}

#Preview {
    LoginView()
}