React Native-navigation.addListner不是对象

Question

App.js：

import React, { Component } from 'react';
import {View,Text} from 'react-native';
import { createDrawerNavigator } from 'react-navigation-drawer';
import {createAppContainer} from 'react-navigation';

import Epics from './screens/tmp';
import Pager from './screens/Pager';

const DrawerNavigator = createDrawerNavigator({
 Home: {screen: Epics},
 Page: {screen: Pager}
},{initialRouteName: 'Home'});

const Stack = createAppContainer(DrawerNavigator);

export default class App extends Component {
  render() {
    return <Stack />;
  }
}

尝试每次使用导航addListner事件在用户登陆屏幕时调用提取API

componentDidMount() {
   this.loadFeed(); // fetch API
   const { navigation } = this.props;
   this.focus = navigation.addListener('willFocus', () => {
     this.loadFeed(); // fetch API
   });
}

来自package.json的反应导航版本：

• “反应导航”：“ ^ 4.2.2”
• “反应导航抽屉”：“ ^ 2.4.2”

是否有更好的方法来检测应用程序上的活动屏幕并调用获取API？或解决以下给定的错误？

类型错误：未定义不是对象（正在评估'navigation.addListner'）：Error when the app launches