Stack Auth Swift SDK

Swift SDK for Stack Auth. Supports iOS, macOS, watchOS, tvOS, and visionOS.

Requirements

• Swift 5.9+
• iOS 15+ / macOS 12+ / watchOS 8+ / tvOS 15+ / visionOS 1+

Installation

Add to your Package.swift:

dependencies: [
    .package(url: "https://github.com/stack-auth/swift-sdk-prerelease", from: <version>)
]

Quick Start

import StackAuth

let stack = StackClientApp(
    projectId: "your-project-id",
    publishableClientKey: "your-key"
)

// Sign in with email/password
try await stack.signInWithCredential(email: "user@example.com", password: "password")

// Get current user
if let user = try await stack.getUser() {
    print("Signed in as \(user.displayName ?? "Unknown")")
}

// Sign out
try await stack.signOut()

Design Decisions

Error Handling

All functions that can fail use Swift's native throws. Errors conform to StackAuthError:

do {
    try await stack.signInWithCredential(email: email, password: password)
} catch let error as StackAuthError {
    switch error.code {
    case "email_password_mismatch":
        print("Wrong password")
    default:
        print(error.message)
    }
}

Token Storage

• Default: Keychain (secure, persists across app launches)
• Option: Memory (for testing or ephemeral sessions)
• Option: Custom TokenStoreProtocol implementation

// Memory storage (for testing)
let stack = StackClientApp(
    projectId: "...",
    publishableClientKey: "...",
    tokenStore: .memory
)

// Custom storage
let stack = StackClientApp(
    projectId: "...",
    publishableClientKey: "...",
    tokenStore: .custom(MyTokenStore())
)

OAuth Flows

Two approaches for OAuth authentication:

1. Integrated (recommended) - Uses ASWebAuthenticationSession:

// Opens auth session, handles callback automatically
// Uses fixed callback scheme: stack-auth-mobile-oauth-url://
try await stack.signInWithOAuth(provider: "google")

2. Manual URL handling - For custom implementations:

Note: The stack-auth-mobile-oauth-url:// scheme is automatically accepted.

// Get the OAuth URL (must provide absolute URLs)
let oauth = try await stack.getOAuthUrl(
    provider: "google",
    redirectUrl: "stack-auth-mobile-oauth-url://success",
    errorRedirectUrl: "stack-auth-mobile-oauth-url://error"
)

// Open oauth.url in your own browser/webview
// Store oauth.state, oauth.codeVerifier, and oauth.redirectUrl

// When callback received:
try await stack.callOAuthCallback(
    url: callbackUrl,
    codeVerifier: oauth.codeVerifier,
    redirectUrl: oauth.redirectUrl
)

Async/Await

All async operations use Swift's native concurrency:

Task {
    let user = try await stack.getUser()
    let teams = try await user?.listTeams()
}

Key Differences from JavaScript SDK

Aspect	JavaScript	Swift
Token Storage	Cookies	Keychain
OAuth	Browser redirect	ASWebAuthenticationSession
Redirect methods	Available	Not available (browser-only)
React hooks	useUser() etc.	Not applicable

Not Available in Swift

The following are browser-only and not exposed:

• redirectToSignIn(), redirectToSignUp(), etc.
• Cookie-based token storage
• redirectMethod constructor option

Examples

Interactive example apps are available for testing all SDK functions:

macOS Example

cd Examples/StackAuthMacOS
swift run

Features a sidebar-based UI for testing authentication, user management, teams, OAuth, tokens, and server-side operations.

iOS Example

cd Examples/StackAuthiOS
open Package.swift  # Opens in Xcode

Features a tab-based UI optimized for iOS with the same comprehensive SDK coverage.

Both examples include:

• Configurable API endpoints
• Real-time operation logs
• Error testing scenarios (wrong password, unauthorized access, etc.)
• Client and server app operations

Testing

Tests use Swift Testing framework against a running backend.

Running Tests

1. Start the development server:

   pnpm dev

2. Run tests:

   cd sdks/implementations/swift
   swift test

The tests connect to http://localhost:8102 (or ${NEXT_PUBLIC_STACK_PORT_PREFIX}02).

API Reference

See the SDK Specification for complete API documentation.