SwiftUI crypto app — qayta ishlatiladigan tarmoq qatlamini yaratish

import Foundation
import Combine

class NetworkingManager {

    // Maxsus xatoliklar enumi (LocalizedError protokoli bilan)
    enum NetworkingError: LocalizedError {
        case badURLResponse(url: URL) // Noto'g'ri server javobi uchun (URL manzili bilan)
        case unknown // Noma'lum xatolik uchun

        // Konsolda ko'rinadigan xato tavsifini o'zgartiramiz
        var errorDescription: String? {
            switch self {
            case .badURLResponse(url: let url):
                return "🔥 Serverdan noto'g'ri javob keldi. URL: \(url.absoluteString)"
            case .unknown:
                return "⚠️ Noma'lum xatolik yuz berdi"
            }
        }
    }

    // Tarmoqdan ma'lumot yuklash uchun umumiy (generic) funksiya
    static func download(url: URL) -> AnyPublisher<Data, Error> {
        return URLSession.shared.dataTaskPublisher(for: url)
            // Fondagi oqimda ishga tushirish
            .subscribe(on: DispatchQueue.global(qos: .default))
            // Server javobini tekshirish uchun yordamchi funksiyani chaqiramiz
            .tryMap({ try handleURLResponse(output: $0, url: url) })
            // Natijani asosiy oqimga (Main Thread) qaytarish
            .receive(on: DispatchQueue.main)
            // Combine zanjiri turlarini yashirish va sodda AnyPublisher qaytarish
            .eraseToAnyPublisher()
    }

    // Server javobini va HTTP status kodini tekshiruvchi funksiya
    static func handleURLResponse(output: URLSession.DataTaskPublisher.Output, url: URL) throws -> Data {
        guard let response = output.response as? HTTPURLResponse,
              response.statusCode >= 200 && response.statusCode < 300 else {
            throw NetworkingError.badURLResponse(url: url)
        }
        return output.data
    }

    // Obunaning yakunlanishini (Completion) boshqaruvchi umumiy funksiya
    static func handleCompletion(completion: Subscribers.Completion<Error>) {
        switch completion {
        case .finished:
            break
        case .failure(let error):
            print(error.localizedDescription)
        }
    }
}

import Foundation
import Combine

class CoinDataService {

    @Published var allCoins: [CoinModel] = []
    private var coinSubscription: AnyCancellable?

    init() {
        getCoins()
    }

    private func getCoins() {
        guard let url = URL(string: "https://api.coingecko.com/api/v3/coins/markets?vs_currency=usd&order=market_cap_desc&per_page=250&page=1&sparkline=true&price_change_percentage=24h") else { return }

        // NetworkingManager-dan foydalanib yuklashni amalga oshiramiz
        coinSubscription = NetworkingManager.download(url: url)
            // Decode amali faqat shu modelga tegishli bo'lgani uchun servis ichida qoladi
            .decode(type: [CoinModel].self, decoder: JSONDecoder())
            .sink(receiveCompletion: NetworkingManager.handleCompletion, receiveValue: { [weak self] (returnedCoins) in
                self?.allCoins = returnedCoins
                self?.coinSubscription?.cancel()
            })
    }
}