Asynchronous download of images and saving in caches directory

UIImageViewExtension.swift

extension UIImageView {
    //Use this function with the imageview
    func loadImageUsingCacheWithUrlString(_ url: String?) {
        guard let url = url else {
            self.image = UIImage(named: "default")
            return
        }
        let imageName = url.split(separator: "/").last! as NSString
        
        let fileManager = FileManager.default
        let diskPaths = NSSearchPathForDirectoriesInDomains(.cachesDirectory, .userDomainMask, true)
        let cacheDirectory = diskPaths[0] as String
        let diskPath = cacheDirectory.appending(imageName as String)
        
        //check cache for image first
        if fileManager.fileExists(atPath: diskPath) {
            self.image = UIImage(contentsOfFile: diskPath)
            return
        }
        
        //otherwise fire off a new download
        URLSession.shared.dataTask(with: URL(string: url)!, completionHandler: { (data, response, error) in
            guard error == nil else {
                print("Image download error:", error?.localizedDescription ?? "")
                return
            }
            DispatchQueue.main.async {
                if let data = data, let image = UIImage(data: data) {
                    try? data.write(to: URL(fileURLWithPath: diskPath), options: .atomic)
                    self.image = image
                }
            }
            
        }).resume()
    }
}

extension UIImageView {
    func downloadedFrom(url: URL, contentMode mode: UIView.ContentMode = .scaleAspectFit) {
        contentMode = mode
        URLSession.shared.dataTask(with: url) { (data, response, error) in
            guard
                let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode == 200,
                let mimeType = response?.mimeType, mimeType.hasPrefix("image"),
                let data = data, error == nil,
                let image = UIImage(data: data)
                else { return }
            DispatchQueue.main.async() {
                self.image = image
            }
        }.resume()
    }
    func downloadedFrom(link: String, contentMode mode: UIView.ContentMode = .scaleAspectFit) {
        guard let url = URL(string: link) else { return }
        downloadedFrom(url: url, contentMode: mode)
    }
}

By @guilhermecolombini