title: React-native component's componentDidMount() is not called under NavigatorIOS
body: <p>I create a component with <code>ListView</code> under the structure: <code>TabBarIOS</code> > <code>NavigatorIOS</code> > <code>ListView</code>. I try to fetch data in <code>componentDidMount()</code>. But it didn't work unless I fetch it in <code>componentWillMount()</code>. Why?</p>
  
  <p>I've put my work here <a href="https://github.com/chiakie/MyAwesomeProject" rel="nofollow noreferrer">https://github.com/chiakie/MyAwesomeProject</a><br/>
  In <code>MotorcycleList.js</code>, <code>componentDidMount()</code> seem to never be called.</p>