改变标题文本和显示/隐藏左/右标题按钮动态点击标签在React Native？

import React from 'react';
import { View, Text, Button } from 'react-native';
import { createStackNavigator } from 'react-navigation';

class HomeScreen extends React.Component {
  static navigationOptions = {
    title: 'Home',
    headerLeft: (
      <Button
        onPress={() => alert('This is a custom left button!')}
        title="Left"
        color="#fff"
      />
    ),
    headerRight: (
      <Button
        onPress={() => alert('This is a custom right button!')}
        title="Right"
        color="#fff"
      />
    ),
  };

  render() {
    return (
      <View>
        <Text>Home Screen</Text>
      </View>
    );
  }
}

const AppNavigator = createStackNavigator({
  Home: {
    screen: HomeScreen,
  },
});

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