title: flutter - How to download asset when apps launched and used it
body: <p>currently, my apps have many assets (images, sound, font, json, SQL-lite database file, etc). All have defined in <code>pubspec.yaml</code></p>
  
  <p>However, due to a request to reduce APK size, I need some of them <strong>to be downloaded when Apps be launched</strong> and save it to storage, so no need to download it next time.</p>
  
  <p>if assets are not yet ready, it should waiting a sec and show loading bar circle.</p>
  
  <p>The question is how to do this thing, Any Example?</p>