simple image cache for iOS

ImageCache.swift

import UIKit

struct ImageCache {
    static func loadImage(url: URL, user: User) async throws -> (UIImage, User) {
        if let cachedImage = InMemoryImageCache.shared.get(forKey: url) {
            return (cachedImage, user)
        }

        let urlRequest = URLRequest(url: url)
        let (data, response) = try await URLSession.shared.data(for: urlRequest)

        if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {
            throw ImageAPIError.unexpected
        }

        if let image = UIImage(data: data) {
            InMemoryImageCache.shared.set(image, forKey: url)
            return (image, user)
        } else {
            throw ImageAPIError.unexpected
        }
    }

    private struct InMemoryImageCache {
        static let shared = InMemoryImageCache()
        private let cache = NSCache<NSURL, UIImage>()

        private init() {}

        func set(_ image: UIImage, forKey url: URL) {
            cache.setObject(image, forKey: url as NSURL)
        }

        func get(forKey url: URL) -> UIImage? {
            return cache.object(forKey: url as NSURL)
        }
    }
}

enum ImageAPIError: Error, LocalizedError {
    case unexpected

    var errorDescription: String? {
        "something happened."
    }
}

final class User: Decodable, Hashable {
    let id: Int64
    let login: String
    let avatarURL: URL?
    let uuid = UUID()
    var image: UIImage = UIImage(named: "placeholder")!

    enum CodingKeys: String, CodingKey {
        case id
        case login
        case avatarURL = "avatar_url"
    }

    public func hash(into hasher: inout Hasher) {
        hasher.combine(uuid)
    }

    static func == (lhs: User, rhs: User) -> Bool {
        lhs.uuid == rhs.uuid
    }
}