title: React Native doesn't update child component props
body: <p>I'm working on a React Native project and I realized that React Native seems to break the React flow (Parent to children) props update.</p>
  
  <p>Basically, I'm calling a "Menu" component from an "App" component, passing a prop to "Menu". However, when I update the "App" state, the props on "Menu" should update, but this doesn't happen. Am I doing something wrong?</p>
  
  <p>That's my code:</p>
  
  <p><strong>App.js</strong></p>
  
  <pre><code>import React from 'react';
  import {
   View,
   Text
  } from 'react-native';
  
  import Menu from './Menu';
  
  class App extends React.Component {
    constructor(props) {
      super(props);
      this.state = {
        opacity: 2
      }
    }
  
    componentDidMount() {
      setTimeout(() =&gt; {
        this.setState({
          opacity: 4
        });
      }, 3000);
    }
  
    render() {
      return(
        &lt;View&gt;
          &lt;Menu propOpacity={this.state.opacity} /&gt;
        &lt;/View&gt;
      );
    }
  }
  
  export default App;
  </code></pre>
  
  <p><strong>Menu.js</strong></p>
  
  <pre><code>import React from 'react';
  import {
  View,
  Text
  } from 'react-native';
  
  class Menu extends React.Component {
    constructor(props) {
      super(props);
      this.state = {
        menuOpacity: props.propOpacity
      }
    }
  
    render() {
      return(
        &lt;View&gt;
          &lt;Text&gt;Menu opacity: {this.state.menuOpacity}&lt;/Text&gt;
        &lt;/View&gt;
      );
    }
  }
  
  Menu.propTypes = {
    propOpacity: React.PropTypes.number
  }
  
  Menu.defaultProps = {
    propOpacity: 1
  }
  
  export default Menu;
  </code></pre>