Auth0 Swift

Auth0 Swift Integration

Auth0.swift is the official Auth0 SDK for Apple platforms (iOS, macOS, tvOS, watchOS, visionOS). This skill adds complete native authentication to Swift apps using Web Auth (system browser redirect), secure Keychain credential storage via CredentialsManager, and optional biometric protection.

When NOT to Use

• Android apps: Use auth0-android
• React Native apps: Use auth0-react-native
• Flutter apps: Use the native Flutter Auth0 SDK
• Web SPAs (React, Angular, Vue): Use auth0-react, auth0-angular, or auth0-vue
• Node.js/Express servers: Use auth0-express

Prerequisites

• iOS 14.0+ / macOS 11.0+ / tvOS 14.0+ / watchOS 7.0+ / visionOS 1.0+
• Xcode 16.x
• Swift 6.0+
• Auth0 account — Sign up free
• Auth0 CLI — brew install auth0/auth0-cli/auth0 (for automated setup)

Quick Start Workflow

Agent instruction: Follow these steps in order. If you encounter an error at any step, attempt to fix it up to 5 times before calling AskUserQuestion to ask the user for guidance. Always search existing code first — if there are existing login/logout handlers, hook into them rather than creating new ones.

IMPORTANT — Credential privacy: Never echo Auth0 credentials (domain, client ID, client secret) in your response text or terminal output. Write them directly into config files using the Write or Edit tool. When running Auth0 CLI commands that produce output containing these values, redirect output to a file and read it programmatically. For example:

auth0 apps create ... --json --no-input > /tmp/auth0-output.json 2>&1

Then use the Read tool on /tmp/auth0-output.json to extract needed values and write them directly into Auth0.plist or other config files — never echo them in response text or terminal. When confirming the active tenant with the user, use a masked format (e.g., your-te****.us.auth0.com).

Step 1 — Install SDK

Agent instruction: Check the project directory for an existing package manager file:

• Podfile present → CocoaPods
• Cartfile present → Carthage
• Package.swift present → Swift Package Manager

If none are found, ask via AskUserQuestion: "Which dependency manager does your project use — Swift Package Manager, CocoaPods, or Carthage?"

Swift Package Manager — Package.swift project: Run this command in the project root to add the dependency automatically, then add "Auth0" to the target's dependencies array in Package.swift:

swift package add-dependency https://github.com/auth0/Auth0.swift --from 2.18.0

Swift Package Manager — Xcode project (.xcodeproj, no Package.swift): The CLI command does not apply. Instruct the user to add the package via Xcode: File → Add Package Dependencies → https://github.com/auth0/Auth0.swift → Up to Next Major Version from 2.18.0.

CocoaPods or Carthage: Follow the matching installation steps in Setup Guide. Do not just show the instructions — perform the file edits and run the commands.

Step 2 — Configure Auth0

Agent instruction:

• If Auth0 credentials (domain AND client ID) are already in the user's prompt: Write Auth0.plist directly with those values — do NOT ask the user any questions, do NOT hardcode them in Swift source files, and do NOT pass them as arguments to Auth0.webAuth() or Auth0.authentication(). The SDK reads Auth0.plist automatically — always use the no-argument form Auth0.webAuth(). Then proceed to Step 3.
• If an Auth0.plist file already exists in the project: Read it to extract ClientId and Domain, then proceed to Step 3.
• If no Auth0.plist exists and no credentials were provided: Ask the user via AskUserQuestion: "How would you like to configure Auth0?"
  • Automatic (Auth0 CLI) — I'll create the application, set callback URLs, and configure everything using the Auth0 CLI.
  • Manual — You provide a pre-configured Auth0.plist file and I'll add it to your project.

If the user chooses automatic: Follow Setup Guide — Automated Setup via Auth0 CLI. If the user chooses manual: Follow Setup Guide — Manual Setup.

Auth0.plist format:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>ClientId</key>
  <string>YOUR_CLIENT_ID</string>
  <key>Domain</key>
  <string>YOUR_DOMAIN</string>
</dict>
</plist>

Place Auth0.plist in the same directory as the app's Swift source files so the SDK can find it automatically.

Step 3 — Configure Callback URLs

Agent instruction:

1. Read Auth0.plist to obtain ClientId and Domain.
2. Extract the bundle identifier from project.pbxproj: search for PRODUCT_BUNDLE_IDENTIFIER, skip values containing $( or Tests.
3. Ask the user via AskUserQuestion: "Which callback URL scheme would you like to use?"
   • Custom scheme ({bundle}://) — simpler, works on all Apple platforms
   • HTTPS Universal Links — recommended for production; prevents URL scheme hijacking

Then follow only the matching path below.

Path A — Custom Scheme

Agent instruction: Register the callback URLs using the Auth0 CLI (substitute real values for CLIENT_ID, BUNDLE_ID, DOMAIN).

First, retrieve existing callback and logout URLs to avoid overwriting them:

auth0 apps show CLIENT_ID --json --no-input > /tmp/auth0-app-info.json 2>&1

Read /tmp/auth0-app-info.json to extract existing callbacks and allowed_logout_urls arrays.

Then include any existing URLs as a comma-separated list alongside the new ones:

auth0 apps update CLIENT_ID \
  --callbacks "EXISTING_CALLBACKS,BUNDLE_ID://DOMAIN/ios/BUNDLE_ID/callback" \
  --logout-urls "EXISTING_LOGOUT_URLS,BUNDLE_ID://DOMAIN/ios/BUNDLE_ID/callback" \
  --no-input > /dev/null 2>&1

If there are no existing URLs, omit the EXISTING_ prefix and use only the new URL.

Then follow the URL scheme registration steps in Setup Guide to register $(PRODUCT_BUNDLE_IDENTIFIER) as a URL type in Xcode.

Path B — HTTPS Universal Links

Agent instruction: All four steps below are required — skipping any one will cause the callback redirect to fail silently after login.

Step B1 — Register callback URLs via Auth0 CLI: Register both HTTPS and custom scheme so the app works in all scenarios.

First, retrieve existing callback and logout URLs to avoid overwriting them:

auth0 apps show CLIENT_ID --json --no-input > /tmp/auth0-app-info.json 2>&1

Read /tmp/auth0-app-info.json to extract existing callbacks and allowed_logout_urls arrays.

Then include any existing URLs as a comma-separated list alongside the new ones:

auth0 apps update CLIENT_ID \
  --callbacks "EXISTING_CALLBACKS,https://DOMAIN/ios/BUNDLE_ID/callback,BUNDLE_ID://DOMAIN/ios/BUNDLE_ID/callback" \
  --logout-urls "EXISTING_LOGOUT_URLS,https://DOMAIN/ios/BUNDLE_ID/callback,BUNDLE_ID://DOMAIN/ios/BUNDLE_ID/callback" \
  --no-input > /dev/null 2>&1

If there are no existing URLs, omit the EXISTING_ prefix and use only the new URLs.

Step B2 — Configure Device Settings via Auth0 CLI: Extract DEVELOPMENT_TEAM from project.pbxproj (10-character value, e.g. ABC12DE34F). If not found, ask via AskUserQuestion: "What is your Apple Team ID? (developer.apple.com → Account → Membership Details)"

auth0 api patch applications/CLIENT_ID \
  --data '{"mobile":{"ios":{"team_id":"TEAM_ID","app_bundle_identifier":"BUNDLE_ID"}}}' \
  --no-input > /dev/null 2>&1

Auth0 will now host the apple-app-site-association file automatically — required for Universal Links to work on device.

Step B3 — Add Associated Domains entitlement in Xcode: Add com.apple.developer.associated-domains to the app's .entitlements file with both applinks: and webcredentials: entries for the Auth0 domain. See Setup Guide — Associated Domains for the complete entitlements XML, Xcode capability steps, and build settings verification.

Step B4 — Use .useHTTPS() in the SDK:

Auth0.webAuth().useHTTPS()

Step 4 — Implement Authentication

Agent instruction: Search the project for @main struct (SwiftUI) or AppDelegate/UIViewController (UIKit) to detect the UI framework. If ambiguous, ask via AskUserQuestion: "Does your app use SwiftUI or UIKit?" Then follow only the matching path below.

IMPORTANT — Never pass credentials in code: Do NOT pass clientId or domain as arguments to Auth0.webAuth(), Auth0.authentication(), or any other SDK call. The SDK reads these values automatically from Auth0.plist. Always use the no-argument forms:

Auth0.webAuth()           // ✓ reads Auth0.plist automatically
Auth0.authentication()    // ✓ reads Auth0.plist automatically

Auth0.webAuth(clientId: "...", domain: "...")      // ✗ never do this
Auth0.authentication(clientId: "...", domain: "...") // ✗ never do this

SwiftUI

Agent instruction: Create AuthenticationService.swift as an ObservableObject, then wire it into the app entry point and root view. Search for the @main struct and ContentView (or equivalent root view) and update them as shown.

// AuthenticationService.swift
import Auth0
import Combine

class AuthenticationService: ObservableObject {
    @Published var isAuthenticated = false
    private let credentialsManager = CredentialsManager(authentication: Auth0.authentication())

    init() { isAuthenticated = credentialsManager.canRenew() }

    func login() async {
        do {
            let credentials = try await Auth0
                .webAuth()
                .useHTTPS()
                .scope("openid profile email offline_access")
                .start()
            _ = credentialsManager.store(credentials: credentials)
            await MainActor.run { isAuthenticated = true }
        } catch WebAuthError.userCancelled { }
        catch { print("Login failed: \(error)") }
    }

    func logout() async {
        do { try await Auth0.webAuth().useHTTPS().clearSession() }
        catch { print("Logout failed: \(error)") }
        _ = credentialsManager.clear()
        await MainActor.run { isAuthenticated = false }
    }
}

// @main App struct — inject AuthenticationService as environment object
@StateObject private var auth = AuthenticationService()
// In body: ContentView().environmentObject(auth)

// Root ContentView — branch on authentication state
@EnvironmentObject var auth: AuthenticationService
// In body: if auth.isAuthenticated { HomeView() } else { LoginView() }

For complete SwiftUI app lifecycle wiring, see Integration Patterns.

UIKit

Agent instruction: Create AuthenticationService.swift as a plain class, then add login/logout calls to the relevant UIViewController. Also check whether the app uses SFSafariViewController — if so, add WebAuthentication.resume(with:) to AppDelegate/SceneDelegate (see note below).

// AuthenticationService.swift
import Auth0

class AuthenticationService {
    private let credentialsManager = CredentialsManager(authentication: Auth0.authentication())

    var isAuthenticated: Bool { credentialsManager.canRenew() }

    func login() async throws {
        let credentials = try await Auth0
            .webAuth()
            .useHTTPS()
            .scope("openid profile email offline_access")
            .start()
        _ = credentialsManager.store(credentials: credentials)
    }

    func logout() async throws {
        try await Auth0.webAuth().useHTTPS().clearSession()
        _ = credentialsManager.clear()
    }
}

// In your UIViewController
private let auth = AuthenticationService()

@IBAction func loginTapped(_ sender: UIButton) {
    Task {
        do {
            try await auth.login()
            await MainActor.run { navigateToHome() }
        } catch WebAuthError.userCancelled { }
        catch { print("Login failed: \(error)") }
    }
}

@IBAction func logoutTapped(_ sender: UIButton) {
    Task {
        do { try await auth.logout() }
        catch { print("Logout failed: \(error)") }
        await MainActor.run { navigateToLogin() }
    }
}

Note — SFSafariViewController only: If the app uses .provider(WebAuthentication.safariProvider()) instead of the default ASWebAuthenticationSession, add WebAuthentication.resume(with: url) to AppDelegate.application(_:open:url:options:) and SceneDelegate.scene(_:openURLContexts:). See Integration Patterns for the exact code.

Step 5 — Verify Build

Agent instruction: Run a build to verify the integration compiles without errors:

xcodebuild build -scheme YOUR_SCHEME -destination "platform=iOS Simulator,name=iPhone 16"

If the build fails, review error messages and fix up to 5 times before asking the user.

Detailed Documentation

• Setup Guide — Auth0 CLI configuration, Auth0.plist, URL scheme registration, Associated Domains, CocoaPods/SPM/Carthage install
• Integration Patterns — Web Auth login/logout, CredentialsManager, biometric protection, MFA, organizations, error handling, SwiftUI/UIKit patterns
• API Reference & Testing — Full API reference, configuration options, claims reference, testing checklist, troubleshooting

Common Mistakes

Related Skills

• auth0-quickstart - Basic Auth0 setup
• auth0-cli - Manage Auth0 resources from the terminal

References

• Auth0.swift GitHub
• iOS/macOS Quickstart
• Auth0.swift API Documentation
• Auth0 Dashboard
• EXAMPLES.md

Source: auth0/agent-skills — distributed by TomeVault.