title: react native picker is not showing in android
body: <p>I am trying to add picker in react native android but it does not showing in android. I map my location date to picker item but i did'nt see picker in screen.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;Picker selectedValue={this.state.location}&gt;
    &lt;Picker.Item label="Location 1" value="1" /&gt; 
    &lt;Picker.Item label="Location 2" value="2" /&gt;
    &lt;Picker.Item label="Location 3" value="3" /&gt;
  &lt;/Picker&gt;</code></pre>
  </div>
  </div>
  </p>