title: this.setState is undefined
body: <p>I keep seeing answers that say to use => or .bind(this) but neither of those solutions worked.</p>
  
  <pre><code>import React, { Component } from 'react';
  import { View, Text, TextInput, StyleSheet } from 'react-native';
  
  export default class MyWeatherApp extends Component {
    constructor(props) {
    super(props);
  
    this.state = {};
  }
  
  getInitialState() {
    return {
      zip: '',
      forecast: null,
    };
  }
  
  _handleTextChange(event) {
    var zip = event.nativeEvent.text;
    this.setState({zip: zip});
  }
  </code></pre>
  
  <p>Solution:</p>
  
  <pre><code>_handleTextChange = (event) =&gt; {
    var zip = event.nativeEvent.text;
    this.setState({zip: zip});
    alert('click');
  }
  </code></pre>