title: Image View Does not display image after setting image to it downloaded from url
body: <p>here it is what i am doing.</p>
  
  <pre><code>extension UIImageView {
      func downloadedFrom(url: URL, contentMode mode: UIViewContentMode = .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: UIViewContentMode = .scaleAspectFit) {
          guard let url = URL(string: link) else { return }
          downloadedFrom(url: url, contentMode: mode)
      }
  </code></pre>
  
  <p>i checked it in image its show image in preview in debug state. but after <code>self.image = image</code> </p>
  
  <p>nothing change on image view image is not displaying. anyone know where the problem is ? thanks </p>