使用React Navigation传递参数的奇怪行为

Here's the screen:

这是屏幕：

import React from 'react';
import { View, StyleSheet, Image, TouchableOpacity, Text } from 'react-native';
import { NavigationActions } from 'react-navigation'

export default class ContentScreen extends React.Component {    
  render() {
    const { state } = this.props.navigation;
    const { code } = state.params.code
    return(
      <Text>CONTENT GOES HERE: {JSON.stringify(state)} / '{code}'</Text>
    )
  }
}
import React from