Authorization and Authentication in Swift: A Complete Guide for iOS/macOS

Authorization and Authentication in Swift: Overview of Tools and Libraries

In iOS and macOS development, user data security is priority number one. Authentication (identity verification) and authorization (granting access rights) are basic components of any modern application. In this article, we will review key tools, libraries, and Swift frameworks for implementing login via Apple ID, third-party services (Google, Facebook), as well as local token storage.

The article is aimed at developers familiar with the basics of Swift and Xcode. All code examples are tested on Swift 5.9+ and are compatible with iOS 17+/macOS 14+.

1. AuthenticationServices: Apple Sign In

Native authorization via Apple ID is a mandatory App Store requirement for applications using third-party providers (Google, Facebook). The AuthenticationServices framework provides a simple API for implementing Sign in with Apple.

import AuthenticationServicesimport SwiftUI

struct SignInWithAppleView: View {    var body: some View {        SignInWithAppleButton(            onRequest: { request in                request.requestedScopes = [.fullName, .email]            },            onCompletion: { result in                switch result {                case .success(let authResults):                    // Get user token                    guard let credential = authResults.credential as? ASAuthorizationAppleIDCredential,                          let tokenData = credential.identityToken,                          let token = String(data: tokenData, encoding: .utf8)                    else { return }                    print("Apple token: \\(token)")                case .failure(let error):                    print("Error: \\(error.localizedDescription)")                }            }        )        .signInWithAppleButtonStyle(.black)        .frame(width: 280, height: 44)    }}

Important: Apple returns fullName and email only on the first login. For subsequent authorizations, use userID from credential.user.

2. Firebase Authentication: Multi-Provider Authentication

Firebase Auth is a cross-platform solution for authorization via email, Google, Facebook, GitHub, and other providers. It includes ready-made UI components and integration with Firestore.

Installation via Swift Package Manager:

// Package.swift or via Xcode: File > Add Packages// URL: https://github.com/firebase/firebase-ios-sdk.git// Select FirebaseAuth, FirebaseFirestore

Example of email/password login:

import FirebaseAuth

func signInWithEmail(email: String, password: String) {    Auth.auth().signIn(withEmail: email, password: password) { authResult, error in        if let error = error {            print("Auth error: \\(error.localizedDescription)")            return        }        guard let user = authResult?.user else { return }        print("User signed in: \\(user.uid)")    }}

func createUser(email: String, password: String) {    Auth.auth().createUser(withEmail: email, password: password) { authResult, error in        // Handle registration    }}

For Google Sign-In, the GoogleSignIn SDK is additionally used. Firebase automatically manages sessions and token refresh.

3. Keychain Services: Secure Token Storage

Storing JWT tokens or refresh tokens in UserDefaults is a serious security mistake. Use Keychain (encrypted storage on iOS/macOS).

Wrapper for Keychain:

import Security

class KeychainManager {    static func save(key: String, data: Data) {        let query: [String: Any] = [            kSecClass as String: kSecClassGener