title: How to open (audio) file from file manager using Flutter app
body: <p>When a user tries to open an audio file from his/her file manager I want to show him/her my app in the following "In which app to open this file" pop-up window. After (s)he selects my app from the pop-up window, I want to pass file path into a state variable (<code>currentSong</code>).</p>
  
  <p>I've already managed to add the following IntentFilter into my AndroidManifest.xml. This should correctly show the user my app in the pop-up window:</p>
  
  <pre><code>&lt;intent-filter&gt;
      &lt;action android:name="android.intent.action.VIEW"/&gt;
      &lt;category android:name="android.intent.category.DEFAULT"/&gt;
      &lt;category android:name="android.intent.category.BROWSABLE"/&gt;
      &lt;data android:scheme="http" /&gt;
      &lt;data android:scheme="content" /&gt;
      &lt;data android:scheme="file" /&gt;
      &lt;data android:mimeType="audio/*" /&gt;
      &lt;data android:mimeType="application/ogg" /&gt;
      &lt;data android:mimeType="application/x-ogg" /&gt;
      &lt;data android:mimeType="application/itunes" /&gt;
  &lt;/intent-filter&gt;
  </code></pre>
  
  <p>But now I'm just clueless. How to get the file path and save it into the state variable <code>currentSong</code> in Flutter?</p>