React Native Reload Screen A In Back action

I Have ScreenA To Click Next ScreenB Then back To Screen A Not Call Function componentWillMount()

ScreenA -> Next -> ScreenB -> Back() -> ScreenA

How to Reload Rout Screen in Back Action

Class ScreenA

import React from "react";
import { Button, Text, View } from "react-native";

class ScreenA extends Component {
  constructor(props){
    super(props)
      this.state = {
        dataSource: new ListView.DataSource({
          rowHasChanged: (row1, row2) => row1 !== row2,
        })
      }
  }

  componentWillMount() {
        fetch(MYCLASS.DEMAND_LIST_URL, {
                method: 'POST',
                headers: {
                  'Accept': 'application/json',
                  'Content-Type': 'application/json',
                },                    
                body: JSON.stringify({
                  userId:'17'})
            })
            .then((response) => response.json())
            .then((responseData) => {
              if (responseData.status == '1') {
                var data =  responseData.data
                this.setState({                  
                  dataSource: this.state.dataSource.cloneWithRows(data),
                });
              }
            })
            .done();
      }


  onPress = () => {
    this.props.navigate("ViewB");
  };

  render() {
    return (
      <View>
        <Text>test</Text>
        <Button title="Next" onPress={this.onPress} />
      </View>
    );
  }
}

Class ScreenB

import React from "react" import { Button } from "react-native"

class ScreenB extends Component {

   render() {
    const {goBack} = this.props.navigation;

    return( 
          <Button title="back" onPress={goBack()} /> 
         )
   }
}