iOS SDK

Native iOS development with Swift and Apple frameworks.

When to Use

• Native iOS apps
• System integrations
• Apple platform features
• Performance-critical apps

Quick Start

import UIKit

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
        return true
    }
}

Core Concepts

App Lifecycle

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    var window: UIWindow?

    func scene(
        _ scene: UIScene,
        willConnectTo session: UISceneSession,
        options connectionOptions: UIScene.ConnectionOptions
    ) {
        guard let windowScene = scene as? UIWindowScene else { return }
        window = UIWindow(windowScene: windowScene)
        window?.rootViewController = MainViewController()
        window?.makeKeyAndVisible()
    }

    func sceneDidEnterBackground(_ scene: UIScene) {
        // Save state
    }
}

Networking

func fetchUser(id: String) async throws -> User {
    let url = URL(string: "https://api.example.com/users/\(id)")!
    let (data, response) = try await URLSession.shared.data(from: url)

    guard let httpResponse = response as? HTTPURLResponse,
          httpResponse.statusCode == 200 else {
        throw NetworkError.invalidResponse
    }

    return try JSONDecoder().decode(User.self, from: data)
}

Common Patterns

UserDefaults

extension UserDefaults {
    enum Key: String {
        case isOnboarded
        case authToken
    }

    var isOnboarded: Bool {
        get { bool(forKey: Key.isOnboarded.rawValue) }
        set { set(newValue, forKey: Key.isOnboarded.rawValue) }
    }
}

Push Notifications

func registerForPushNotifications() {
    UNUserNotificationCenter.current().requestAuthorization(
        options: [.alert, .badge, .sound]
    ) { granted, _ in
        guard granted else { return }
        DispatchQueue.main.async {
            UIApplication.shared.registerForRemoteNotifications()
        }
    }
}

func application(
    _ application: UIApplication,
    didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data
) {
    let token = deviceToken.map { String(format: "%02.2hhx", $0) }.joined()
    // Send token to server
}

Best Practices

Do:

• Use async/await for networking
• Respect user privacy
• Support accessibility
• Handle edge cases

Don't:

• Block main thread
• Force unwrap optionals
• Ignore error handling
• Skip device testing

Troubleshooting

Issue	Cause	Solution
UI freeze	Main thread blocked	Use async
Memory warning	Leaks	Use Instruments
Crash on launch	Missing permissions	Add Info.plist keys

References

• Apple Developer Docs
• App Store Guidelines