The Rejection Reason (Guideline 4.8 - Sign in with Apple)
This rule is simple but ruthless. If your app offers a third-party login system (Google, Facebook, Twitter/X, LinkedIn), you are absolutely required to offer "Sign in with Apple" as an equivalent option.
Why this rule?
Apple wants to guarantee its users the ability to log in anonymously (by hiding their true email address) and securely, without being forced to give their data to web giants or your company.
Exceptions (When you are NOT required)
- You only use your own authentication system (Exclusive Email/Password).
- You are an enterprise app (B2B) requiring a company account (e.g., Microsoft Entra ID) for employees.
- You are an existing government or education app.
The Solution for Capacitor
Use the reliable community plugin: @capacitor-community/apple-sign-in.
- Configure the "Service ID" and private key in your Apple Developer portal.
- Add the official black or white " Sign in with Apple" button to your UI (Apple is very strict on button design, follow their SVG guidelines).
- Handle the returned token to authenticate the user on your backend (e.g., Supabase, Firebase, or your own API).