title: Save MP3-files from server to specific folder in react native project
body: <p>I am creating <strong>MP3 player</strong> app for a customer.</p>
  <p>The app has a playlist of mp3-files that is stored on a server. The user should be able to download some of these mp3-files to a local folder in the app and play it from there. The app need also have control of the size of this download folder and give the user a warning when this folder hit a specific size limit, so the user then can decide to delete files in the folder.</p>
  <p>I am trying to use <code>react-native-fetch-blob</code></p>
  <p>And have tried this code in a click-function:</p>
  <pre class="lang-js prettyprint-override"><code>let dirs = RNFetchBlob.fs.dirs
  RNFetchBlob
  .config({
    // response data will be saved to this path if it has access right.
    path : dirs.DocumentDir + '/path-to-file.anything'
  })
  .fetch('GET', 'https://www.xa-speakers.org/pafiledb.php?action=download&amp;id=2', {
    //some headers ..
  })
  .then((res) =&gt; {
    // the path should be dirs.DocumentDir + 'path-to-file.anything'
    console.log('The file saved to ', res.path())
  })
  </code></pre>
  <p>But nothing happens and I got nothing in console.log?</p>
  <p>Have followed instructions on installing <code>react-native-fetch-blob</code></p>
  <p>Does it Mather that the file is on https - server?</p>
  <p>When I use <code>react-native-fetch-blob</code> how does the file stores? In a folder? Can I store multi-files in same folder?</p>
  <p>Is there others easy way to download mp3-files from server and store it in local folder in the app?</p>
  <p>Thanks,
  Kaj</p>