iOS Mulakat Hazirlik Rehberi: Junior'dan Senior'a

1// Value type - kopyalanir
2struct Point {
3    var x: Double
4    var y: Double
5}
6 
7var p1 = Point(x: 1, y: 2)
8var p2 = p1        // KOPYA
9p2.x = 10
10print(p1.x)       // 1 (degismedi)
11print(p2.x)       // 10
12 
13// Reference type - referans paylasilir
14class Node {
15    var value: Int
16    init(value: Int) { self.value = value }
17}
18 
19let n1 = Node(value: 1)
20let n2 = n1        // AYNI REFERANS
21n2.value = 10
22print(n1.value)    // 10 (degisti!)

1var name: String? = "Ali"
2 
3// 1. Force unwrap (TEHLIKELI)
4let forced = name!
5 
6// 2. Optional binding (if let)
7if let unwrapped = name {
8    print(unwrapped)
9}
10 
11// 3. Guard let (early exit)
12guard let safeName = name else { return }
13print(safeName)
14 
15// 4. Nil coalescing
16let displayName = name ?? "Misafir"
17 
18// 5. Optional chaining
19let count = name?.count // Int?
20 
21// 6. Map / flatMap
22let uppercased = name.map { item in item.uppercased() } // String?

1// Non-escaping: fonksiyon bitince closure da biter
2func syncOperation(completion: () -> Void) {
3    completion()
4}
5 
6// Escaping: closure fonksiyon bittikten SONRA calisabilir
7func asyncOperation(completion: @escaping () -> Void) {
8    DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
9        completion() // Fonksiyon coktan bitti, closure hala yasiyor
10    }
11}

1class CustomView: UIView {
2    // 1. Olusturma
3    override init(frame: CGRect) { super.init(frame: frame) }
4    required init?(coder: NSCoder) { super.init(coder: coder) }
5 
6    // 2. Layout
7    override func layoutSubviews() {
8        super.layoutSubviews()
9        // Frame-based layout hesaplamalari
10    }
11 
12    // 3. Cizim
13    override func draw(_ rect: CGRect) {
14        // Custom drawing (Core Graphics)
15    }
16 
17    // 4. Trait degisikligi
18    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
19        super.traitCollectionDidChange(previousTraitCollection)
20        // Dark mode, size class degisikligi
21    }
22}

1struct ParentView: View {
2    @State private var count = 0           // Sahiplik burada
3    @StateObject private var vm = MyVM()   // ViewModel sahipligi
4 
5    var body: some View {
6        ChildView(count: $count, vm: vm)   // Referans gecir
7    }
8}
9 
10struct ChildView: View {
11    @Binding var count: Int                // Disaridan gelen state referansi
12    @ObservedObject var vm: MyVM           // Disaridan gelen ViewModel
13    @Environment(\.colorScheme) var scheme // Cevre degiskeni
14 
15    var body: some View {
16        Text("Count: \(count)")
17    }
18}

1// Data race ornegi (TEHLIKELI)
2class UnsafeCounter {
3    var value = 0
4    func increment() { value += 1 }
5}
6 
7// Actor ile guvenli (DOGRU)
8actor SafeCounter {
9    var value = 0
10    func increment() { value += 1 }
11    func getValue() -> Int { value }
12}
13 
14// Kullanim
15let counter = SafeCounter()
16await counter.increment()       // await zorunlu
17let val = await counter.getValue()

1// Structured concurrency
2func fetchDashboard() async throws -> Dashboard {
3    async let profile = fetchProfile()
4    async let orders = fetchOrders()
5    async let notifications = fetchNotifications()
6 
7    return try await Dashboard(
8        profile: profile,
9        orders: orders,
10        notifications: notifications
11    )
12}
13 
14// TaskGroup ile dinamik parallelism
15func fetchAllPages() async throws -> [Page] {
16    try await withThrowingTaskGroup(of: Page.self) { group in
17        for i in 1...10 {
18            group.addTask {
19                try await self.fetchPage(i)
20            }
21        }
22 
23        var pages: [Page] = []
24        for try await page in group {
25            pages.append(page)
26        }
27        return pages.sorted { a, b in a.number < b.number }
28    }
29}

1// Retain cycle ornegi
2class ViewController {
3    var onComplete: (() -> Void)?
4 
5    func setup() {
6        // HATALI: self'i strong capture eder
7        onComplete = {
8            self.updateUI() // retain cycle!
9        }
10 
11        // DOGRU: weak capture
12        onComplete = { [weak self] in
13            guard let self else { return }
14            self.updateUI()
15        }
16    }
17 
18    func updateUI() { }
19}
20 
21// Delegate pattern'de weak kullanimi
22protocol DataDelegate: AnyObject {
23    func didReceiveData(_ data: Data)
24}
25 
26class DataManager {
27    weak var delegate: DataDelegate? // WEAK olmali
28}

1// Constructor injection (en yaygin)
2class UserService {
3    private let repository: UserRepository
4    private let validator: UserValidator
5 
6    init(repository: UserRepository, validator: UserValidator) {
7        self.repository = repository
8        self.validator = validator
9    }
10}
11 
12// Test'te mock kullanimi
13let mockRepo = MockUserRepository()
14let service = UserService(repository: mockRepo, validator: RealValidator())

1// Modern async/await yaklasimi
2func fetchUser(id: String) async throws -> User {
3    let url = URL(string: "https://api.example.com/users/" + id)!
4    var request = URLRequest(url: url)
5    request.httpMethod = "GET"
6    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
7 
8    let (data, response) = try await URLSession.shared.data(for: request)
9 
10    guard let httpResponse = response as? HTTPURLResponse,
11          (200...299).contains(httpResponse.statusCode) else {
12        throw NetworkError.invalidResponse
13    }
14 
15    return try JSONDecoder().decode(User.self, from: data)
16}