title: How to refresh the previous screen when I goBack()
body: <p>I'm new to react-native. Now I need to implement a function in two screens. When I click a bottom in the "addActivity" scene, it will go back to the "homeScene" which is the previous scene of "addActivity" and show the data from "addActivity" scene. </p>
  
  <p>I try to store the data in "addActivity" scene by a map:</p>
  
  <pre><code>export const m = new Map();
  </code></pre>
  
  <p>And import the map in homeScene scene</p>
  
  <pre><code>import { m } from './addActivity';
  </code></pre>
  
  <p>I'm not sure this way is good. I saw there are some functions of react-native-navigation can pass parameters but I don't know how to use them.
  Now the biggest is how to refresh the "homeScene" scene when I use goBack() from "addActivity" scene.
  <strong>There is the code of the two scenes</strong></p>
  
  <p>homeScene.js</p>
  
  <pre><code>import React, { Component } from 'react';
  import {
      AppRegistry,
      StyleSheet,
      Text,
      TextInput,
      View,
      TouchableOpacity,
      Dimensions
  } from 'react-native';
  
  import { m } from './addActivity';
  
  
  export default class LeftSideMenu extends Component {
      constructor(props) {
          super(props);
  
          this.state = {
              isOpen: false,
          }
  
      add = () =&gt; {
          const { navigate } = this.props.navigation;  
          navigate('Add');  
      }
  
  render() {
          return (
  
                  &lt;View style={styles.container}&gt;
                      //I want to show the data here
                      &lt;Text
                          style={styles.btText2}&gt;{m.get("title")}&lt;/Text&gt;
  
                      //This is the bottom to jump to "addActivity" scene
                      &lt;TouchableOpacity
                          onPress={this.add} 
                          style={styles.Addbutton}&gt;
                          &lt;Text
                              style={styles.btText2}&gt;+&lt;/Text&gt;
                      &lt;/TouchableOpacity&gt;
                  &lt;/View&gt;
  
          );
  
      }
  }
  </code></pre>
  
  <p>addActivity.js</p>
  
  <pre><code>import React, { Component } from 'react';
  import { View, ScrollView, Dimensions, StyleSheet, Text, Button, TouchableOpacity, Alert } from 'react-native';
  
  import { NavigationPage, ListRow, Input, Select, Label } from 'teaset';
  
  let { height, width } = Dimensions.get('window');
  
  //initial the map
  export const m = new Map();
  
  export default class InputExample extends Component {
  
  
    constructor(props) {
      super(props);
      this.state = {
        length: 0,
        title: '',
        isVisible: false,
      };
      Object.assign(this.state, {
        valueTitle: null,
      });
    }
  
  
  //Return  to homeScene
    homeScene = () =&gt; {
      m.set("title", this.valueTitle);
      const { goBack } = this.props.navigation; 
      Alert.alert("Add succeed","return to Homepage",[{text: 'confirm', onPress: () =&gt; { goBack(); }}]) 
  
    }
  
    render() {
      return (
        &lt;ScrollView style={{ flex: 1 }}&gt;
  
          &lt;ListRow title='Title *' detail={
            &lt;Input
              style={{ width: 200 }}
              size='md'
              value={this.state.valueMD}
              placeholder=''
              onChangeText={text =&gt; this.setState({ valueTitle: text })}
            /&gt;
          } topSeparator='full' /&gt;
  
          &lt;TouchableOpacity
            onPress={this.homeScene} 
            style={styles.button}&gt;
            &lt;Text
              style={styles.btText}&gt;Confirm&lt;/Text&gt;
          &lt;/TouchableOpacity&gt;
  
        &lt;/ScrollView&gt;
      );
    }
  }
  </code></pre>
  
  <p>I expect when I use goBack() to the homeScene the scene can refresh and the data from addActivity scene can be printed on homeScene</p>