UIImageView load from URL, placeholder and cache

UIImageView+loadFromURL-extension.swift

extension UIImageView {
    func setImage(from url: URL, withPlaceholder placeholder: UIImage? = .none, withCache cache:NSCache<NSURL,UIImage>? = .none) -> URLSessionDataTask? {
        
        if let cached = cache?.object(forKey: url as NSURL) {
            self.image = cached
            return .none
        }
        
        self.image = placeholder
        let task = URLSession.shared.dataTask(with: url)  { (data, _, _) in
            if let data = data, let image = UIImage(data: data) {
                cache?.setObject(image, forKey: url as NSURL)
                DispatchQueue.main.async {
                    self.image = image
                }
            }
        }
        task.resume()
        return task
    }
}