Network Layer Optimization: Production-Ready API Katmanı Oluşturma Rehberi

1// MARK: - Endpoint Protocol
2protocol Endpoint {
3    var baseURL: URL { get }
4    var path: String { get }
5    var method: HTTPMethod { get }
6    var headers: [String: String] { get }
7    var parameters: Parameters? { get }
8    var encoding: ParameterEncoding { get }
9}
10 
11enum HTTPMethod: String {
12    case get = "GET"
13    case post = "POST"
14    case put = "PUT"
15    case patch = "PATCH"
16    case delete = "DELETE"
17}
18 
19enum Parameters {
20    case body([String: Any])
21    case query([String: String])
22}
23 
24enum ParameterEncoding {
25    case json
26    case url
27}
28 
29// MARK: - API Endpoints
30enum ProductAPI: Endpoint {
31    case list(page: Int, limit: Int)
32    case detail(id: UUID)
33    case create(product: ProductRequest)
34    case update(id: UUID, product: ProductRequest)
35    case delete(id: UUID)
36    case search(query: String, filters: ProductFilters?)
37    
38    var baseURL: URL {
39        URL(string: "https://api.myapp.com/v1")!
40    }
41    
42    var path: String {
43        switch self {
44        case .list: return "/products"
45        case .detail(let id): return "/products/\(id)"
46        case .create: return "/products"
47        case .update(let id, _): return "/products/\(id)"
48        case .delete(let id): return "/products/\(id)"
49        case .search: return "/products/search"
50        }
51    }
52    
53    var method: HTTPMethod {
54        switch self {
55        case .list, .detail, .search: return .get
56        case .create: return .post
57        case .update: return .put
58        case .delete: return .delete
59        }
60    }
61    
62    var headers: [String: String] {
63        var headers = [
64            "Content-Type": "application/json",
65            "Accept": "application/json",
66            "X-API-Version": "1.0"
67        ]
68        if let token = AuthManager.shared.accessToken {
69            headers["Authorization"] = "Bearer \(token)"
70        }
71        return headers
72    }
73    
74    var parameters: Parameters? {
75        switch self {
76        case .list(let page, let limit):
77            return .query(["page": "\(page)", "limit": "\(limit)"])
78        case .create(let product), .update(_, let product):
79            return .body(product.dictionary)
80        case .search(let query, let filters):
81            var params = ["q": query]
82            if let filters = filters {
83                params.merge(filters.queryParams) { _, new in new }
84            }
85            return .query(params)
86        default:
87            return nil
88        }
89    }
90    
91    var encoding: ParameterEncoding {
92        switch method {
93        case .get: return .url
94        default: return .json
95        }
96    }
97}

1// MARK: - Network Service Protocol
2protocol NetworkServiceProtocol {
3    func request<T: Decodable>(_ endpoint: Endpoint) async throws -> T
4    func request(_ endpoint: Endpoint) async throws -> Data
5}
6 
7// MARK: - Network Errors
8enum NetworkError: LocalizedError {
9    case invalidURL
10    case noData
11    case decodingError(Error)
12    case serverError(statusCode: Int, message: String?)
13    case unauthorized
14    case notFound
15    case rateLimited(retryAfter: TimeInterval?)
16    case noConnection
17    case timeout
18    case unknown(Error)
19    
20    var errorDescription: String? {
21        switch self {
22        case .invalidURL: return "Geçersiz URL"
23        case .noData: return "Veri alınamadı"
24        case .decodingError(let error): return "Veri işlenemedi: \(error.localizedDescription)"
25        case .serverError(let code, let message): return "Sunucu hatası (\(code)): \(message ?? "Bilinmeyen hata")"
26        case .unauthorized: return "Oturum süresi doldu"
27        case .notFound: return "İçerik bulunamadı"
28        case .rateLimited: return "Çok fazla istek gönderildi"
29        case .noConnection: return "İnternet bağlantısı yok"
30        case .timeout: return "İstek zaman aşımına uğradı"
31        case .unknown(let error): return error.localizedDescription
32        }
33    }
34}
35 
36// MARK: - Network Service Implementation
37actor NetworkService: NetworkServiceProtocol {
38    static let shared = NetworkService()
39    
40    private let session: URLSession
41    private let decoder: JSONDecoder
42    private let cache: URLCache
43    
44    private init() {
45        // Custom URLSession configuration
46        let config = URLSessionConfiguration.default
47        config.timeoutIntervalForRequest = 30
48        config.timeoutIntervalForResource = 60
49        config.waitsForConnectivity = true
50        config.requestCachePolicy = .returnCacheDataElseLoad
51        
52        // Cache configuration (50MB memory, 100MB disk)
53        cache = URLCache(
54            memoryCapacity: 50 * 1024 * 1024,
55            diskCapacity: 100 * 1024 * 1024
56        )
57        config.urlCache = cache
58        
59        session = URLSession(configuration: config)
60        
61        // JSON Decoder configuration
62        decoder = JSONDecoder()
63        decoder.keyDecodingStrategy = .convertFromSnakeCase
64        decoder.dateDecodingStrategy = .iso8601
65    }
66    
67    func request<T: Decodable>(_ endpoint: Endpoint) async throws -> T {
68        let data = try await request(endpoint)
69        
70        do {
71            return try decoder.decode(T.self, from: data)
72        } catch {
73            throw NetworkError.decodingError(error)
74        }
75    }
76    
77    func request(_ endpoint: Endpoint) async throws -> Data {
78        let request = try buildRequest(from: endpoint)
79        
80        do {
81            let (data, response) = try await session.data(for: request)
82            
83            guard let httpResponse = response as? HTTPURLResponse else {
84                throw NetworkError.unknown(NSError(domain: "Invalid response", code: -1))
85            }
86            
87            try validateResponse(httpResponse, data: data)
88            
89            return data
90        } catch let error as NetworkError {
91            throw error
92        } catch let error as URLError {
93            throw mapURLError(error)
94        } catch {
95            throw NetworkError.unknown(error)
96        }
97    }
98    
99    private func buildRequest(from endpoint: Endpoint) throws -> URLRequest {
100        var urlComponents = URLComponents(url: endpoint.baseURL.appendingPathComponent(endpoint.path), resolvingAgainstBaseURL: true)
101        
102        // Query parameters
103        if case .query(let params) = endpoint.parameters {
104            urlComponents?.queryItems = params.map { URLQueryItem(name: $0.key, value: $0.value) }
105        }
106        
107        guard let url = urlComponents?.url else {
108            throw NetworkError.invalidURL
109        }
110        
111        var request = URLRequest(url: url)
112        request.httpMethod = endpoint.method.rawValue
113        request.allHTTPHeaderFields = endpoint.headers
114        
115        // Body parameters
116        if case .body(let params) = endpoint.parameters {
117            request.httpBody = try JSONSerialization.data(withJSONObject: params)
118        }
119        
120        return request
121    }
122    
123    private func validateResponse(_ response: HTTPURLResponse, data: Data) throws {
124        switch response.statusCode {
125        case 200...299:
126            return
127        case 401:
128            throw NetworkError.unauthorized
129        case 404:
130            throw NetworkError.notFound
131        case 429:
132            let retryAfter = response.value(forHTTPHeaderField: "Retry-After")
133                .flatMap { TimeInterval($0) }
134            throw NetworkError.rateLimited(retryAfter: retryAfter)
135        case 500...599:
136            let message = try? JSONDecoder().decode(ErrorResponse.self, from: data).message
137            throw NetworkError.serverError(statusCode: response.statusCode, message: message)
138        default:
139            throw NetworkError.serverError(statusCode: response.statusCode, message: nil)
140        }
141    }
142    
143    private func mapURLError(_ error: URLError) -> NetworkError {
144        switch error.code {
145        case .notConnectedToInternet, .networkConnectionLost:
146            return .noConnection
147        case .timedOut:
148            return .timeout
149        default:
150            return .unknown(error)
151        }
152    }
153}

1actor RetryableNetworkService {
2    private let networkService: NetworkServiceProtocol
3    private let maxRetries: Int
4    private let baseDelay: TimeInterval
5    
6    init(
7        networkService: NetworkServiceProtocol = NetworkService.shared,
8        maxRetries: Int = 3,
9        baseDelay: TimeInterval = 1.0
10    ) {
11        self.networkService = networkService
12        self.maxRetries = maxRetries
13        self.baseDelay = baseDelay
14    }
15    
16    func request<T: Decodable>(_ endpoint: Endpoint) async throws -> T {
17        var lastError: Error?
18        
19        for attempt in 0..<maxRetries {
20            do {
21                return try await networkService.request(endpoint)
22            } catch let error as NetworkError {
23                lastError = error
24                
25                // Non-retryable errors
26                switch error {
27                case .unauthorized, .notFound, .decodingError:
28                    throw error
29                case .rateLimited(let retryAfter):
30                    if let delay = retryAfter {
31                        try await Task.sleep(nanoseconds: UInt64(delay * 1_000_000_000))
32                    }
33                default:
34                    // Exponential backoff
35                    let delay = baseDelay * pow(2.0, Double(attempt))
36                    let jitter = Double.random(in: 0...0.5)
37                    try await Task.sleep(nanoseconds: UInt64((delay + jitter) * 1_000_000_000))
38                }
39            }
40        }
41        
42        throw lastError ?? NetworkError.unknown(NSError(domain: "Max retries exceeded", code: -1))
43    }
44}

1// MARK: - Cache Manager
2actor CacheManager {
3    static let shared = CacheManager()
4    
5    private var memoryCache: [String: CacheEntry] = [:]
6    private let fileManager = FileManager.default
7    private let cacheDirectory: URL
8    
9    private init() {
10        cacheDirectory = fileManager.urls(for: .cachesDirectory, in: .userDomainMask)[0]
11            .appendingPathComponent("NetworkCache")
12        
13        try? fileManager.createDirectory(at: cacheDirectory, withIntermediateDirectories: true)
14    }
15    
16    func get<T: Decodable>(_ key: String) async -> T? {
17        // Memory cache first
18        if let entry = memoryCache[key],
19           entry.expiresAt > Date(),
20           let value = entry.value as? T {
21            return value
22        }
23        
24        // Disk cache
25        let fileURL = cacheDirectory.appendingPathComponent(key.sha256)
26        guard let data = try? Data(contentsOf: fileURL),
27              let cached = try? JSONDecoder().decode(CachedItem<T>.self, from: data),
28              cached.expiresAt > Date() else {
29            return nil
30        }
31        
32        // Populate memory cache
33        memoryCache[key] = CacheEntry(value: cached.value, expiresAt: cached.expiresAt)
34        
35        return cached.value
36    }
37    
38    func set<T: Encodable>(_ value: T, for key: String, ttl: TimeInterval = 300) async {
39        let expiresAt = Date().addingTimeInterval(ttl)
40        
41        // Memory cache
42        memoryCache[key] = CacheEntry(value: value, expiresAt: expiresAt)
43        
44        // Disk cache
45        let cached = CachedItem(value: value, expiresAt: expiresAt)
46        if let data = try? JSONEncoder().encode(cached) {
47            let fileURL = cacheDirectory.appendingPathComponent(key.sha256)
48            try? data.write(to: fileURL)
49        }
50    }
51    
52    func invalidate(_ key: String) async {
53        memoryCache.removeValue(forKey: key)
54        let fileURL = cacheDirectory.appendingPathComponent(key.sha256)
55        try? fileManager.removeItem(at: fileURL)
56    }
57    
58    func clearAll() async {
59        memoryCache.removeAll()
60        try? fileManager.removeItem(at: cacheDirectory)
61        try? fileManager.createDirectory(at: cacheDirectory, withIntermediateDirectories: true)
62    }
63}
64 
65private struct CacheEntry {
66    let value: Any
67    let expiresAt: Date
68}
69 
70private struct CachedItem<T: Codable>: Codable {
71    let value: T
72    let expiresAt: Date
73}

1// MARK: - Repository with Offline Support
2class ProductRepository {
3    private let networkService: NetworkServiceProtocol
4    private let cacheManager: CacheManager
5    private let reachability: NetworkReachability
6    
7    init(
8        networkService: NetworkServiceProtocol = NetworkService.shared,
9        cacheManager: CacheManager = .shared,
10        reachability: NetworkReachability = .shared
11    ) {
12        self.networkService = networkService
13        self.cacheManager = cacheManager
14        self.reachability = reachability
15    }
16    
17    func getProducts(page: Int = 1) async throws -> [Product] {
18        let cacheKey = "products_page_\(page)"
19        
20        // Offline: return cached data
21        if !reachability.isConnected {
22            if let cached: [Product] = await cacheManager.get(cacheKey) {
23                return cached
24            }
25            throw NetworkError.noConnection
26        }
27        
28        // Online: fetch and cache
29        do {
30            let response: ProductListResponse = try await networkService.request(
31                ProductAPI.list(page: page, limit: 20)
32            )
33            await cacheManager.set(response.products, for: cacheKey, ttl: 600)
34            return response.products
35        } catch {
36            // Fallback to cache on error
37            if let cached: [Product] = await cacheManager.get(cacheKey) {
38                return cached
39            }
40            throw error
41        }
42    }
43}

1// MARK: - Request Interceptor
2protocol RequestInterceptor {
3    func intercept(_ request: inout URLRequest) async throws
4}
5 
6// Auth Token Interceptor
7class AuthInterceptor: RequestInterceptor {
8    func intercept(_ request: inout URLRequest) async throws {
9        guard let token = await AuthManager.shared.getValidToken() else {
10            throw NetworkError.unauthorized
11        }
12        request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
13    }
14}
15 
16// Logging Interceptor
17class LoggingInterceptor: RequestInterceptor {
18    func intercept(_ request: inout URLRequest) async throws {
19        #if DEBUG
20        print("🌐 [\(Date())] \(request.httpMethod ?? "?") \(request.url?.absoluteString ?? "?")")
21        #endif
22    }
23}
24 
25// Interceptor Chain
26class InterceptorChain {
27    private var interceptors: [RequestInterceptor] = []
28    
29    func add(_ interceptor: RequestInterceptor) {
30        interceptors.append(interceptor)
31    }
32    
33    func process(_ request: inout URLRequest) async throws {
34        for interceptor in interceptors {
35            try await interceptor.intercept(&request)
36        }
37    }
38}

1import Network
2 
3actor NetworkMonitor {
4    static let shared = NetworkMonitor()
5    private let monitor = NWPathMonitor()
6    
7    private(set) var isConnected = true
8    private(set) var connectionType: ConnectionType = .unknown
9    
10    enum ConnectionType { case wifi, cellular, ethernet, unknown }
11    
12    func startMonitoring() {
13        monitor.pathUpdateHandler = { [weak self] path in
14            Task { await self?.updatePath(path) }
15        }
16        monitor.start(queue: DispatchQueue(label: "NetworkMonitor"))
17    }
18    
19    private func updatePath(_ path: NWPath) {
20        isConnected = path.status == .satisfied
21        
22        if path.usesInterfaceType(.wifi) { connectionType = .wifi }
23        else if path.usesInterfaceType(.cellular) { connectionType = .cellular }
24        else { connectionType = .unknown }
25        
26        NotificationCenter.default.post(name: .networkStatusChanged, object: nil)
27    }
28}
29 
30extension Notification.Name {
31    static let networkStatusChanged = Notification.Name("networkStatusChanged")
32}