How do I support Apple login in my app?

To support Sign in with Apple, you usually need both client-side UI and server-side token verification.

1) Create a Sign in with Apple capability

In Apple Developer:

• Enable Sign in with Apple for your App ID
• Add the capability in Xcode:
  • iOS/macOS: Signing & Capabilities → + Capability → Sign In with Apple

2) Add the Apple sign-in button

Use Apple’s official button style:

• Sign in with Apple Button
• Don’t customize it heavily; Apple requires specific appearance rules

3) Start the authorization request

On iOS, use AuthenticationServices:

import AuthenticationServices

let appleIDProvider = ASAuthorizationAppleIDProvider()
let request = appleIDProvider.createRequest()
request.requestedScopes = [.fullName, .email]

let authorizationController = ASAuthorizationController(authorizationRequests: [request])
authorizationController.delegate = self
authorizationController.presentationContextProvider = self
authorizationController.performRequests()

4) Handle the result

Implement delegate callbacks:

extension YourViewController: ASAuthorizationControllerDelegate {
    func authorizationController(controller: ASAuthorizationController,
                                 didCompleteWithAuthorization authorization: ASAuthorization) {
        if let credential = authorization.credential as? ASAuthorizationAppleIDCredential {
            let userIdentifier = credential.user
            let email = credential.email
            let fullName = credential.fullName
            let identityToken = credential.identityToken
            let authorizationCode = credential.authorizationCode

            // Send identityToken / authorizationCode to your backend
        }
    }

    func authorizationController(controller: ASAuthorizationController,
                                 didCompleteWithError error: Error) {
        // Handle failure/cancel
    }
}

5) Verify on your backend

Send the identity token and/or authorization code to your server, then:

• Verify Apple’s JWT signature using Apple’s public keys
• Check claims like:
  • iss == https://appleid.apple.com
  • aud matches your app/client ID
  • token is not expired
• Create or log in the user in your system

6) Store the Apple user identifier

Use credential.user as the stable Apple user ID for your app.

• Store it securely in your database
• It stays stable for your app/team, but may differ across bundle IDs/services

7) Account linking

If the user already has an account in your app:

• Link Apple sign-in to that account
• Avoid creating duplicate accounts

8) Important Apple-specific notes

• Apple may only provide email/full name the first time
• Use email as optional, not guaranteed
• If you offer third-party login (Google/Facebook/etc.), Apple may require Sign in with Apple as well for iOS apps in some cases

---

If you want a quick implementation checklist

• Enable capability in Apple Developer + Xcode
• Add official Apple sign-in button
• Request .fullName and .email
• Receive ASAuthorizationAppleIDCredential
• Send token to backend
• Verify JWT/signature on server
• Create/link user account
• Use credential.user as stable identifier

If you tell me your stack (iOS Swift, Android, web, Flutter, React Native, backend language), I can give you a concrete implementation example.