ViewController.swift

import UIKit
import Combine

...
class ViewController: UIViewController {
    ...
    
    override func viewDidLoad() {
        ...
    }
    
    private func getAvatarFromTheServer() -> AnyPublisher<UIImage, Error> {
        
        // 1
        let url = URL(string: "https://picsum.photos/1000")!
        
        // 2
        return Deferred {
            Future { promise in
                DispatchQueue.global().async {
                    guard let data = try? Data(contentsOf: url),
                        let image = UIImage(data: data) else {
                            // 3
                            promise(.failure(CustomError.dataCorrupted))
                            return
                        }
                
                    // 4
                    promise(.success(image))
                }
            }
        }.eraseToAnyPublisher()
    }
}