iOS Design Patterns: Pratik Örneklerle 15 Tasarım Deseni

1// Apple'ın singleton'ları
2UIApplication.shared
3FileManager.default
4UserDefaults.standard
5NotificationCenter.default
6 
7// Kendi singleton'ımız - Thread-safe
8final class AnalyticsManager {
9    static let shared = AnalyticsManager()
10 
11    private let queue = DispatchQueue(label: "analytics", qos: .utility)
12    private var events: [AnalyticsEvent] = []
13 
14    private init() {} // Dışarıdan instance oluşturmayı engelle
15 
16    func track(_ event: AnalyticsEvent) {
17        queue.async { [weak self] in
18            self?.events.append(event)
19            if self?.events.count ?? 0 >= 10 {
20                self?.flush()
21            }
22        }
23    }
24 
25    private func flush() {
26        let batch = events
27        events.removeAll()
28        // API'ye gönder...
29    }
30}

1// Factory Method
2protocol ViewControllerFactory {
3    func makeListVC() -> UIViewController
4    func makeDetailVC(item: Item) -> UIViewController
5}
6 
7class ProductViewControllerFactory: ViewControllerFactory {
8    func makeListVC() -> UIViewController {
9        let vm = ProductListViewModel(repository: ProductRepository())
10        return ProductListViewController(viewModel: vm)
11    }
12 
13    func makeDetailVC(item: Item) -> UIViewController {
14        let vm = ProductDetailViewModel(product: item as! Product)
15        return ProductDetailViewController(viewModel: vm)
16    }
17}
18 
19// Abstract Factory - Platform-specific UI
20protocol UIComponentFactory {
21    func makeButton(title: String) -> any ButtonComponent
22    func makeTextField(placeholder: String) -> any TextFieldComponent
23    func makeAlert(title: String, message: String) -> any AlertComponent
24}
25 
26class iOSComponentFactory: UIComponentFactory {
27    func makeButton(title: String) -> any ButtonComponent { iOSButton(title: title) }
28    func makeTextField(placeholder: String) -> any TextFieldComponent { iOSTextField(placeholder: placeholder) }
29    func makeAlert(title: String, message: String) -> any AlertComponent { iOSAlert(title: title, message: message) }
30}

1class URLRequestBuilder {
2    private var url: URL
3    private var method: String = "GET"
4    private var headers: [String: String] = [:]
5    private var body: Data?
6    private var timeout: TimeInterval = 30
7 
8    init(url: URL) { self.url = url }
9 
10    @discardableResult
11    func method(_ method: String) -> Self { self.method = method; return self }
12 
13    @discardableResult
14    func header(_ key: String, _ value: String) -> Self { headers[key] = value; return self }
15 
16    @discardableResult
17    func jsonBody<T: Encodable>(_ body: T) -> Self {
18        self.body = try? JSONEncoder().encode(body)
19        headers["Content-Type"] = "application/json"
20        return self
21    }
22 
23    @discardableResult
24    func timeout(_ seconds: TimeInterval) -> Self { self.timeout = seconds; return self }
25 
26    func build() -> URLRequest {
27        var request = URLRequest(url: url, timeoutInterval: timeout)
28        request.httpMethod = method
29        request.httpBody = body
30        headers.forEach { request.setValue($1, forHTTPHeaderField: $0) }
31        return request
32    }
33}
34 
35// Kullanım - fluent API
36let request = URLRequestBuilder(url: apiURL)
37    .method("POST")
38    .header("Authorization", "Bearer \(token)")
39    .jsonBody(CreateUserRequest(name: "John", email: "[email protected]"))
40    .timeout(15)
41    .build()

1// Adapter - 3rd party kütüphaneyi kendi interface'imize uyarla
2protocol AnalyticsService {
3    func logEvent(_ name: String, parameters: [String: Any])
4}
5 
6// Firebase adapter
7class FirebaseAnalyticsAdapter: AnalyticsService {
8    func logEvent(_ name: String, parameters: [String: Any]) {
9        Analytics.logEvent(name, parameters: parameters)
10    }
11}
12 
13// Mixpanel adapter
14class MixpanelAnalyticsAdapter: AnalyticsService {
15    func logEvent(_ name: String, parameters: [String: Any]) {
16        Mixpanel.mainInstance().track(event: name, properties: parameters as? Properties)
17    }
18}
19 
20// Facade - Karmaşık alt sistemi basit interface ile sar
21class AppStartupFacade {
22    private let analytics: AnalyticsService
23    private let crashReporter: CrashReporter
24    private let featureFlags: FeatureFlagService
25    private let pushManager: PushNotificationManager
26 
27    init(analytics: AnalyticsService, crashReporter: CrashReporter,
28         featureFlags: FeatureFlagService, pushManager: PushNotificationManager) {
29        self.analytics = analytics
30        self.crashReporter = crashReporter
31        self.featureFlags = featureFlags
32        self.pushManager = pushManager
33    }
34 
35    func start() async {
36        crashReporter.initialize()
37        await featureFlags.fetch()
38        pushManager.requestPermission()
39        analytics.logEvent("app_launched", parameters: [:])
40    }
41}

1// Protocol
2protocol DataService {
3    func fetchData() async throws -> [Item]
4}
5 
6// Base implementation
7class RemoteDataService: DataService {
8    func fetchData() async throws -> [Item] {
9        // Network request...
10        return try await apiClient.fetch()
11    }
12}
13 
14// Caching decorator
15class CachingDataService: DataService {
16    private let wrapped: DataService
17    private let cache: NSCache<NSString, CacheEntry>
18 
19    init(wrapping service: DataService) {
20        self.wrapped = service
21        self.cache = NSCache()
22    }
23 
24    func fetchData() async throws -> [Item] {
25        if let cached = cache.object(forKey: "items"), !cached.isExpired {
26            return cached.items
27        }
28        let items = try await wrapped.fetchData()
29        cache.setObject(CacheEntry(items: items), forKey: "items")
30        return items
31    }
32}
33 
34// Logging decorator
35class LoggingDataService: DataService {
36    private let wrapped: DataService
37 
38    init(wrapping service: DataService) { self.wrapped = service }
39 
40    func fetchData() async throws -> [Item] {
41        let start = CFAbsoluteTimeGetCurrent()
42        let items = try await wrapped.fetchData()
43        let elapsed = CFAbsoluteTimeGetCurrent() - start
44        print("📊 Fetched \(items.count) items in \(elapsed)s")
45        return items
46    }
47}
48 
49// Compose decorators
50let service: DataService = LoggingDataService(
51    wrapping: CachingDataService(
52        wrapping: RemoteDataService()
53    )
54)

1// Observer - Combine ile modern iOS
2class ShoppingCart: ObservableObject {
3    @Published var items: [CartItem] = []
4    @Published var totalPrice: Decimal = 0
5 
6    func addItem(_ item: CartItem) {
7        items.append(item)
8        recalculateTotal()
9    }
10}
11 
12// Strategy Pattern - Farklı sıralama algoritmaları
13protocol SortStrategy {
14    func sort<T: Comparable>(_ array: [T]) -> [T]
15}
16 
17struct QuickSortStrategy: SortStrategy {
18    func sort<T: Comparable>(_ array: [T]) -> [T] { array.sorted() }
19}
20 
21struct RelevanceSortStrategy: SortStrategy {
22    func sort<T: Comparable>(_ array: [T]) -> [T] { array.reversed() }
23}
24 
25class ProductListViewModel {
26    var sortStrategy: SortStrategy = QuickSortStrategy()
27 
28    func sortProducts(_ products: [Product]) -> [Product] {
29        // Strategy pattern ile runtime'da algoritma değiştir
30        sortStrategy.sort(products)
31    }
32}

1protocol Coordinator: AnyObject {
2    var childCoordinators: [Coordinator] { get set }
3    var navigationController: UINavigationController { get }
4    func start()
5}
6 
7class AppCoordinator: Coordinator {
8    var childCoordinators: [Coordinator] = []
9    let navigationController: UINavigationController
10 
11    init(navigationController: UINavigationController) {
12        self.navigationController = navigationController
13    }
14 
15    func start() {
16        if UserDefaults.standard.bool(forKey: "isLoggedIn") {
17            showMain()
18        } else {
19            showAuth()
20        }
21    }
22 
23    private func showAuth() {
24        let authCoordinator = AuthCoordinator(nav: navigationController)
25        authCoordinator.onLoginSuccess = { [weak self] in
26            self?.removeChild(authCoordinator)
27            self?.showMain()
28        }
29        childCoordinators.append(authCoordinator)
30        authCoordinator.start()
31    }
32 
33    private func showMain() {
34        let mainCoordinator = MainTabCoordinator(nav: navigationController)
35        childCoordinators.append(mainCoordinator)
36        mainCoordinator.start()
37    }
38 
39    private func removeChild(_ coordinator: Coordinator) {
40        childCoordinators.removeAll { $0 === coordinator }
41    }
42}

1protocol ProductRepository {
2    func getAll() async throws -> [Product]
3    func getById(_ id: UUID) async throws -> Product
4    func save(_ product: Product) async throws
5    func delete(_ id: UUID) async throws
6}
7 
8class RemoteProductRepository: ProductRepository {
9    private let apiClient: APIClient
10 
11    func getAll() async throws -> [Product] {
12        try await apiClient.get("/products")
13    }
14 
15    func getById(_ id: UUID) async throws -> Product {
16        try await apiClient.get("/products/\(id)")
17    }
18 
19    func save(_ product: Product) async throws {
20        try await apiClient.post("/products", body: product)
21    }
22 
23    func delete(_ id: UUID) async throws {
24        try await apiClient.delete("/products/\(id)")
25    }
26}