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

Authorization and Authentication in Swift (iOS/macOS)

Authorization and authentication are key components of any modern application. In the Apple ecosystem (iOS/macOS), developers have access to powerful frameworks and libraries that simplify these processes. In this article, we will cover the main approaches, popular libraries, and provide practical examples in Swift.

Basic Concepts

Before moving to code, it is important to distinguish between two terms:

• Authentication — verifying a user's identity (e.g., login + password, Face ID, Touch ID).
• Authorization — determining access rights after authentication (e.g., whether a user can view certain data).

Built-in Apple Capabilities

1. LocalAuthentication (Face ID / Touch ID)

The LocalAuthentication framework allows using the device's biometric data for authentication.

import LocalAuthentication

func authenticateWithBiometrics() {    let context = LAContext()    var error: NSError?        // Check if biometrics is available    guard context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) else {        print("Biometrics unavailable: \\(error?.localizedDescription ?? "error")")        return    }        // Request authentication    context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: "Log in to access the app") { success, authError in        DispatchQueue.main.async {            if success {                print("Authentication successful")            } else {                print("Error: \\(authError?.localizedDescription ?? "unknown error")")            }        }    }}

2. Keychain Services

Keychain is a secure storage for passwords and tokens. Use it to store credentials after authentication.

import Security

func saveToKeychain(service: String, account: String, password: String) {    guard let passwordData = password.data(using: .utf8) else { return }        let query: [String: Any] = [        kSecClass as String: kSecClassGenericPassword,        kSecAttrService as String: service,        kSecAttrAccount as String: account,        kSecValueData as String: passwordData    ]        // Delete old data if any    SecItemDelete(query as CFDictionary)        // Add new data    let status = SecItemAdd(query as CFDictionary, nil)    if status == errSecSuccess {        print("Data saved to Keychain")    } else {        print("Save error: \\(status)")    }}

func readFromKeychain(service: String, account: String) -> String? {    let query: [String: Any] = [        kSecClass as String: kSecClassGenericPassword,        kSecAttrService as String: service,        kSecAttrAccount as String: account,        kSecReturnData as String: true,        kSecMatchLimit as String: kSecMatchLimitOne    ]        var item: CFTypeRef?    let status = SecItemCopyMatching(query as CFDictionary, &item)        guard status == errSecSuccess, let data = item as? Data else {        return nil    }    return String(data: data, encoding: .utf8)}

Popular Libraries for Authorization

1. Firebase Authentication

Firebase provides a ready-made solution for authentication via email/password, Google, Apple, Facebook, and other providers.

import FirebaseAuth

func signInWithEmail(email: String, password: String) {    Auth.auth().signIn(withEmail: email, password: password) { result, error in        if let error = error {            print("Login error: \\(error.localizedDescription)")            return        }        print("User logged in: \\(result?.user.uid ?? "none")")    }