title: Ant Design Mobile Picker doesn't pop up from bottom when used in React Native
body: <p>I was testing the Picker component from Ant Design Mobile with React Native. But the Picker doesn't pop up from the bottom of the screen like it does in the demo (<a href="https://mobile.ant.design/components/picker/" rel="nofollow noreferrer">https://mobile.ant.design/components/picker/</a>) when I pressed it.</p>
  
  <p>I first defined an array of data:</p>
  
  <pre><code>const testData = [
      {value: 1, label: '1'},
      {value: 2, label: '2'},
      {value: 3, label: '3'},
  ]; 
  </code></pre>
  
  <p>Then I included the Picker component in the render method:</p>
  
  <pre><code>&lt;Picker
      data={testData}
      values={[1]}
      cols={1}&gt;
      &lt;List.Item arrow="horizontal"&gt;Option&lt;/List.Item&gt;
  &lt;/Picker&gt;
  </code></pre>
  
  <p>But when I pressed on the 'Option' field on screen, nothing happened. The picker didn't pop up.</p>
  
  <p>Interestingly, though, when I put the DatePicker component in the render method simply like this:</p>
  
  <pre><code>&lt;DatePicker&gt;
      &lt;List.Item&gt;Pick a Date&lt;/List.Item&gt;
  &lt;/DatePicker&gt;
  </code></pre>
  
  <p>The DatePicker did pop up when I pressed it.</p>
  
  <p>So I don't know what I did wrong here. How do I fix this?</p>