ReferenceError:can not find variable:React

代码如下：

import {createStackNavigator, createAppContainer, createBottomTabNavigator} from "react-navigation";
import HomeScreen from "../pages/home";
import MineScreen from "../pages/mine";
import DetailsScreen from "../pages/details";
// import React from 'react';

import TabIconBottom from "../components/init/tab_bottom";

const homeNavigator = createStackNavigator(
  {
    Home: HomeScreen,
    Details: DetailsScreen,

  }
);

const mineNavigator = createStackNavigator(
  {
    Mine:MineScreen
  }
);

const bottomNavigator = createBottomTabNavigator(
  {
    TabHome: {
      screen:homeNavigator,
      navigationOptions:{
        tabBarIcon:({title,focused})=>{
          return 
        }
      }

    },
    TabMine:mineNavigator
  },
  {
    initialRouteName: 'TabHome',
  }
);

export default createAppContainer(bottomNavigator);

报错信息：

image.png

出错原因：在代码中使用了TabIconBottom,这是jsx语法，必须引入React
解决办法：将头部的注释打开即可

import React from 'react';