title: Add placeholder to a network image in flutter
body: <h3>I have many network images that are being displayed in my app.</h3>
  <p><em>When these images are being loaded... Nothing shows on the screen (the screen remains blank for about 3-5 seconds, time for the image to be displayed)</em></p>
  <h3>How to show something like a loader or animation while the image is being loaded?</h3>