title: undefined is not a function (evaluating 'fetch('apiurl')')
body: <p>I am using below versions</p>
  
  <ol>
  <li>react-native-router-flux ^3.39.1 </li>
  <li>react-native 0.44.0</li>
  </ol>
  
  <p>I expecting that will call API which I am using with "fetch"
  Have used componentDidMount but it's showing another error</p>
  
  <blockquote>
    <p>undefined is not an object (evaluating 'this._component.getScrollableNode')</p>
  </blockquote>
  
  <p>But I am getting below error outputs</p>
  
  <p><a href="https://i.stack.imgur.com/ifFuo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ifFuo.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/WUuKT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/WUuKT.png" alt="enter image description here"></a></p>
  
  <p>Steps to reproduce</p>
  
  <ol>
  <li>Create three scene using router flux (In my case App, Login, Home)</li>
  <li>Use ScrollView for creating the Login.js Create a button </li>
  <li>using TouchableHighlight after that call the fetch with a function
  using onPress like <code>onPress={ () =&gt; this.fetchData() }</code></li>
  </ol>
  
  <p>Below code, I am using for App.js</p>
  
  <pre><code>import React, { Component } from 'react';
  import {
      View,
      Text,
      StyleSheet,
      AsyncStorage,
  } from 'react-native';
  
  import Login from './components/Login'
  import Register from './components/Register'
  import Home from './components/Home'
  import { Scene, Router, TabBar, Modal, Schema, Actions, Reducer, ActionConst } from 'react-native-router-flux'
  
  const reducerCreate = params=&gt;{
      const defaultReducer = Reducer(params);
      return (state, action)=&gt;{
          console.log("ACTION:", action);
          return defaultReducer(state, action);
      }
  };
  
  export default class App extends Component {
  
      constructor(props, context) {
          super(props, context);
          this.state = {
              logged: false,
              loading: true,
          };
      };
  
      componentWillMount(){
          self = this;
          AsyncStorage.getItem('token')
          .then( (value) =&gt;{
              if (value != null){
                  this.setState({
                      logged: true,
                      loading: false,
                  });
              }
              else {
                  this.setState({
                      loading: false,
                  })
              }
          });
      };
  
      render() {
          if (this.state.loading) {
              return &lt;View&gt;&lt;Text&gt;Loading&lt;/Text&gt;&lt;/View&gt;;
          }
          return (
              &lt;Router&gt;
                  &lt;Scene hideNavBar={true} key="root"&gt;
                      &lt;Scene key="logIn" component={Login} title="Login" initial={!this.state.logged}/&gt;
                      &lt;Scene key="regisTer" component={Register} title="Register"/&gt;
                      &lt;Scene key="home" component={Home} title="home"  initial={this.state.logged}/&gt;
                  &lt;/Scene&gt;
              &lt;/Router&gt;
          )
      }
  }
  
  const styles = StyleSheet.create({
      container: {
          flex: 1,
      },
  });
  </code></pre>
  
  <p>And below code, using for Login.js</p>
  
  <pre><code>/* @flow */
  
  import React, { Component } from 'react';
  
  import {
      View,
      StyleSheet,
      Image,
      ScrollView,
      TextInput,
      Text,
      TouchableHighlight,
      Alert,
  } from 'react-native';
  import { Container, Content, InputGroup, Input, Icon, Item } from 'native-base';
  import Button from 'react-native-button'
  import {Actions} from 'react-native-router-flux'
  import ResponsiveImage from 'react-native-responsive-image'
  
  export default class Login extends Component {
  
      constructor(props){
          super(props)
          this.state = {
              email: '',
              password: '',
              data: '',
          }
      }
  
      fetchData() {
          fetch('http://allstariq.tbltechnerds.com/api/login/?username=andress&amp;password=23434')
          .then((response) =&gt; response.json())
          .then((responseData) =&gt; {
              this.setState({
                  data: responseData.movies,
              });
          })
          .done();
      }
  
      render() {
          return (
              &lt;View style={styles.container}&gt;
  
              &lt;ScrollView&gt;
  
                  &lt;View style={ styles.logoContainer }&gt;
  
                      &lt;View style={{flexDirection: 'row',}}&gt;
                          &lt;ResponsiveImage
                          source={require('../assets/logo.png')}
                          initWidth="300"
                          initHeight="160" /&gt;
                      &lt;/View&gt;
  
                  &lt;/View&gt;
  
                  &lt;View style={ styles.formContainer }&gt;
                      &lt;Item&gt;
                          &lt;Icon active name='mail' /&gt;
                          &lt;Input
                              onChangeText={(text) =&gt; this.setState({email: text})}
                              value={this.state.email}
                              placeholder='Email'/&gt;
                      &lt;/Item&gt;
  
                      &lt;Item&gt;
                          &lt;Icon active name='key' /&gt;
                          &lt;Input
                              onChangeText={(text) =&gt; this.setState({password: text})}
                              value={this.state.password}
                              placeholder='Password'/&gt;
                      &lt;/Item&gt;
                      &lt;TouchableHighlight
                          style={ styles.loginButton }
                          onPress={ () =&gt; this.fetchData() }&gt;
                          &lt;Text style={ styles.btnText}&gt;Login&lt;/Text&gt;
                      &lt;/TouchableHighlight&gt;
                  &lt;/View&gt;
  
                  &lt;View style={ styles.bottomContainer }&gt;
                      &lt;Text style={ styles.cenText }&gt;Dont worry if you haven't an account yet . . &lt;/Text&gt;
                      &lt;Text
                      style={ styles.blueText}
                      onPress={ Actions.regisTer }
                      &gt;Register Now&lt;/Text&gt;
                  &lt;/View&gt;
  
              &lt;/ScrollView&gt;
  
              &lt;/View&gt;
          );
      }
  }
  
  const styles = StyleSheet.create({
      container: {
          flex: 1,
      },
      logoContainer: {
          flex: .5,
          padding: 10,
          justifyContent: 'center',
          alignItems: 'center',
      },
      logoItem: {
          width: null,
          height: null,
          resizeMode: 'cover',
      },
      formContainer: {
          flex: 4,
          padding: 10,
      },
      inputelm: {
          marginBottom: 10,
          backgroundColor: '#999',
          borderWidth: 0,
          fontSize: 20,
          color: '#FFF',
          fontFamily: 'AmaticSC-Bold',
      },
      loginButton: {
          borderRadius: 3,
          marginBottom: 20,
          marginTop: 20,
          paddingLeft: 10,
          paddingRight: 10,
          backgroundColor: '#2196f3',
          elevation: 4,
      },
      signupButton: {
          borderRadius: 3,
          marginBottom: 20,
          marginTop: 20,
          paddingLeft: 10,
          paddingRight: 10,
          backgroundColor: '#7cb342',
          elevation: 4,
      },
      btnText: {
          textAlign: 'center',
          color: '#FFF',
          fontSize: 30,
          lineHeight: 40,
      },
      blueText: {
          textAlign: 'center',
          color: '#2196f3',
          fontSize: 20,
          lineHeight: 40,
      },
      bottomContainer: {
          flex: 1,
          padding: 10,
      },
      cenText: {
          textAlign: 'center',
          fontSize: 16,
      },
  });
  </code></pre>
  
  <p>What is the actual way to use fetch with react-native-router-flux? I am new to react, please help me.</p>