Choosing an iOS Login Strategy: Sign in with Apple vs. Email vs. Social Login

If your iOS app offers Google or Facebook login, App Review will require you to also offer Sign in with Apple — and if you implement it carelessly, you'll lose the user's name and email on the very first sign-in. This guide walks through the actual decision: which authentication options are on the table, what each one costs you, and how to implement the Apple flow correctly on your backend.

The decision and its constraints

The core constraint is an App Store Review policy: if your app offers any third-party or social login, you must also offer Sign in with Apple. Apps that use only their own email/password account system are exempt. This means the decision is really three options:

The practical takeaway: if you want any social login at all, budget for Sign in with Apple from day one. Retrofitting it after App Review rejects an update is a worse experience than building it in initially.

Trade-offs that bite in production

First-sign-in data loss. Apple delivers the user's full name and email only on the very first authorization. Subsequent authorizations return only the identity token. If your backend doesn't persist that first payload immediately, it's gone — there is no API to fetch it later.

Hide My Email. Users can choose a private relay address ending in @privaterelay.appleid.com. You must treat this as a valid, deliverable address. You cannot match it to the user's real email, and you should never use email as your account key for Apple sign-ins.

The stable identifier is sub. The identity token's sub claim is stable per user per developer team. Store this as your primary mapping, not the email, which can change or be a relay alias.

Account deletion. App Store policy requires apps with account creation to offer in-app deletion. For Apple sign-ins, you should also revoke the user's tokens via Apple's REST endpoint when they delete their account.

Implementing the token exchange correctly

On the client, request credentials with ASAuthorizationAppleIDProvider, asking for the fullName and email scopes. You get back an authorization code (single-use, short-lived) and an identity token (a JWT).

The critical rule: never trust the identity token client-side. Send it to your server, which must:

1. Fetch Apple's public keys from Apple's JWKS endpoint.
2. Verify the JWT signature against those keys.
3. Check iss (Apple's issuer), aud (your app's bundle ID), and exp.
4. Extract sub and look up or create the account. On first sign-in, persist the name and email from the client payload in the same transaction.

If you need server-issued access or refresh tokens, exchange the authorization code via Apple's token endpoint promptly — it expires quickly and can't be replayed.

How to validate before submitting

Run these checks on a sandbox build with a test Apple ID:

• Request fullName and email scopes; confirm name/email appear only on the first authorization and that your backend persisted them.
• On the server, log the verified sub across two sign-ins and confirm it's identical.
• Choose "Hide My Email" during sign-in and confirm your system stores the relay address and can deliver mail to it.
• Exercise your in-app account deletion path and confirm token revocation is called.

Limitations

App Review enforcement details and the Sign in with Apple REST API evolve. Before submitting, check the current App Store Review Guidelines sections on Sign in with Apple and account deletion rather than relying on any article — including this one — for the current policy text.