title: this refs is getting undefined in method
body: <p>I am trying to use this plugin in my project <a href="https://github.com/rt2zz/react-native-drawer">https://github.com/rt2zz/react-native-drawer</a>. I could run the example properly but having problem integrating it.</p>
  
  <p>I am getting error in method openDrawer. "Can not read property drawer of undefined"</p>
  
  <p>I am guessing that I am not defining and using the class in the right way as it should be ( i'm new to javascript OOP ) as in example it use <code>React.createClass({</code> unlike mine as extending Component and have constructor.</p>
  
  <p>Relevant codes from my class are as follow. </p>
  
  <pre><code>class Search extends Component {
  
      constructor(props) {
          super(props);
          this.state = {
              isLoading: true,
              dataSource: new ListView.DataSource({
                 rowHasChanged: (row1, row2) =&gt; row1 !== row2
              })
          };
      }
  
      openDrawer(){
          this.refs.drawer.open()
      }
  
      getInitialState(){
          return {
            drawerType: 'overlay',
  
          }
      }
  </code></pre>
  
  <p>Render are</p>
  
  <pre><code>render() {
          if (this.state.isLoading) {
              return this.renderLoadingView();
          }
  
          var controlPanel = &lt;MyControlPanel closeDrawer={() =&gt; {this.refs.drawer.close()}} /&gt;
  
          return (
  
  
              &lt;View&gt;
                  &lt;View style={styles.topBar}&gt;
  
                      &lt;Drawer
                          ref="drawer"
                          &gt;
                          &lt;MyMainView
                            /&gt;
                      &lt;/Drawer&gt;
  
                      &lt;Text style={styles.topBarMenu}&gt;&amp;#9776;&lt;/Text&gt;
                      &lt;Text style={styles.topBarTitle}&gt;เงินปันผล&lt;/Text&gt;
                      &lt;Text style={styles.topBarRight}&gt;&lt;/Text&gt;
                  &lt;/View&gt;
  </code></pre>