Building a Client App From Scratch - Image download extension

ImagesManager.swift

import UIKit
import Alamofire

class ImageManager {

    private let session = Alamofire.Session()
    
    static let shared = ImageManager()

    func load(url: URLConvertible, completionHandler: @escaping (UIImage) -> Void) -> Void {
        session.request(url).responseData(
            queue: DispatchQueue.global(),
            completionHandler: { response in
                if let data = response.data, let image = UIImage(data: data) {
                    DispatchQueue.main.async {
                        completionHandler(image)
                    }
                }
        })
    }
}

UIImageView+extension.swift

import UIKit
import Alamofire

extension UIImageView {
    func load(url: URLConvertible) {
        backgroundColor = .lightGray
        image = nil

        ImageManager.shared.load(url: url) { [weak self] image in
            self?.backgroundColor = nil
            self?.image = image
        }
    }
}