title: TouchableHighlight press error
body: <p>I'm new to react-native, I'm just trying to play around with actions and states.
  I don't get where's the problem in this component.</p>
  
  <p>I get the error <code>undefined is not an object (evaluating 'this.wrappedInstance.setNativeProps')</code></p>
  
  <pre><code>import React, { Component } from 'react';
  import { Container, Text } from 'native-base';
  import {
      AppRegistry,
      View,
      TouchableHighlight
  } from 'react-native';
  
  export default class Page2 extends Component {
      constructor(){
          super();
          this.state  = {
              mess: "Page 2 message"
          }
      }
      onPress(){
          this.state.mess = this.state.mess+" wow a click!"
      }
      render() {
          return (
              &lt;View&gt;
                  &lt;TouchableHighlight
                      onPress={this.onPress}
                      underlayColor="blue"
                  &gt;
                  &lt;Text&gt; {this.state.mess}&lt;/Text&gt;
                  &lt;/TouchableHighlight&gt;
              &lt;/View&gt;
          );
      }
  }
  AppRegistry.registerComponent('Page2', () =&gt; Page2);
  </code></pre>