title: Get key and item onPress TouchableOpacity when items are map
body: <p>In below code items are rendered properly and working<br>
  But When I Press <strong>TouchableOpacity</strong> it returns event.<br>
  I Used <strong>JSON.stringify(event.nativeEvent)</strong> but not working</p>
  
  <p>I want to get the <strong>key value</strong> that set on TouchableOpacity and that item Data.</p>
  
  <pre><code>export default class MyLanguages extends Component {
      constructor(props) {
        super(props);
        this.state = {
          languageData: ["English","Hindi","Tamil","Telugu","Gujarati","Marathi","Panjabi"],
        };
      }
      render() {
          return (
              &lt;View style={styles.container}&gt;
                  {this.state.languageData.map( (item,index) =&gt; {
                      return (
                          &lt;TouchableOpacity key={index}
                              onPress={ (event)=&gt;{
                                  alert(event.nativeEvent)
                              }}&gt;
                              &lt;Text style={MyStyle.appFontStyle2}&gt;{item}&lt;/Text&gt;
                          &lt;/TouchableOpacity&gt;
                      )}
                  )}
              &lt;/View&gt;
          )
      }
  }
  </code></pre>