# Authentication

Implement iOS authentication flows with AuthenticationServices and LocalAuthentication.

- Repository: https://github.com/dpearson2699/swift-ios-skills (1266 stars)
- Category: Mobile
- License: see repository
- Last updated: 2026-07-31
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add dpearson2699/swift-ios-skills --skill authentication -g -a claude-code -y`
Codex: `npx skills add dpearson2699/swift-ios-skills --skill authentication -g -a codex -y`
Cursor: `npx skills add dpearson2699/swift-ios-skills --skill authentication -g -a cursor -y`
Gemini CLI: `npx skills add dpearson2699/swift-ios-skills --skill authentication -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add dpearson2699/swift-ios-skills`

## Description

Implement iOS authentication flows with AuthenticationServices and LocalAuthentication. Use when building Sign in with Apple, passkey/WebAuthn registration or sign-in with ASAuthorizationPlatformPublicKeyCredentialProvider, ASAuthorizationController credential state and revocation handling, ASWebAuthenticationSession OAuth or third-party login, Password AutoFill, identity-token server validation, or local biometric re-authentication with LAContext.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Authentication

Implement authentication flows on iOS using the AuthenticationServices
framework, including Sign in with Apple, passkeys, OAuth/third-party web
auth, Password AutoFill, and biometric re-authentication.

## Contents

- [Sign in with Apple](#sign-in-with-apple)
- [Credential Handling](#credential-handling)
- [Credential State Checking](#credential-state-checking)
- [Token Validation](#token-validation)
- [Existing Account Setup Flows](#existing-account-setup-flows)
- [Passkeys](#passkeys)
- [ASWebAuthenticationSession (OAuth)](#aswebauthenticationsession-oauth)
- [Password AutoFill Credentials](#password-autofill-credentials)
- [Biometric Authentication](#biometric-authentication)
- [Security Boundaries](#security-boundaries)
- [SwiftUI SignInWithAppleButton](#swiftui-signinwithapplebutton)
- [Common Mistakes](#common-mistakes)
- [Review Checklist](#review-checklist)
- [References](#references)

## Sign in with Apple

Add the "Sign in with Apple" capability in Xcode before using these APIs.

### UIKit: ASAuthorizationController Setup

```swift
import AuthenticationServices

final class LoginViewController: UIViewController {
    func startSignInWithApple() {
        let provider = ASAuthorizationAppleIDProvider()
        let request = provider.createRequest()
        request.requestedScopes = [.fullName, .email]

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

extension LoginViewController: ASAuthorizationControllerPresentationContextProviding {
    func presentationAnchor(for controller: ASAuthorizationController) -> ASPresentationAnchor {
        view.window!
    }
}
```

### Delegate: Handling Success and Failure

The rest: https://github.com/dpearson2699/swift-ios-skills/blob/HEAD/skills/authentication/SKILL.md