2.2.3 修改JSX代码

/** * Sample React Native App * https://github.com/facebook/react-native * @flow */import React, { Component } from ‘react‘;import { ?AppRegistry, ?StyleSheet, ?Text, ?View} from ‘react-native‘;export default class MyProject8 extends Component { ?render() { ???return ( ?????<View style={styles.container}> ???????<Text style={styles.welcome}> ?????????Welcome to React Native! ???????</Text> ???????<Text style={styles.instructions}> ?????????To get started, edit index.android.js ???????</Text> ???????<Text style={styles.instructions}> ?????????Double tap R on your keyboard to reload,{‘\n‘} ?????????Shake or press menu button for dev menu ???????</Text> ?????</View> ???); ?}}const styles = StyleSheet.create({ ?container: { ???flex: 1, ???justifyContent: ‘center‘, ???alignItems: ‘center‘, ???backgroundColor: ‘#F5FCFF‘, ?}, ?welcome: { ???fontSize: 20, ???textAlign: ‘center‘, ???margin: 10, ?}, ?instructions: { ???textAlign: ‘center‘, ???color: ‘#333333‘, ???marginBottom: 5, ?},});AppRegistry.registerComponent(‘MyProject8‘, () => MyProject8);

/** * Sample React Native App * https://github.com/facebook/react-native * @flow */import React, { Component } from ‘react‘;import { //为了节约版面,将下面的多行写为一行,读者可以不修改 ?AppRegistry, ?StyleSheet, ?Text, ?View} from ‘react-native‘;let Dimensions = require(‘Dimensions‘); ????????????????????//请读者增加此行代码let PixelRatio = require(‘PixelRatio‘); ????????????????????//请读者增加此行代码let totalWidth = Dimensions.get(‘window‘).width; ???????????//请读者增加此行代码let totalHeight = Dimensions.get(‘window‘).height; ?????????//请读者增加此行代码let pixelRatio = PixelRatio.get(); ?????????????????????????//请读者增加此行代码export default class MyProject8 extends Component { ?render() { ???return ( ?????<View style={styles.container}> ???????<Text style={styles.welcome}> ?????????pixelRatio = {pixelRatio} ???????????????????????????//需要修改的第一行 ???????</Text> ???????<Text style={styles.instructions}> ?????????totalHeight = {totalHeight}; ????????????????????????//需要修改的第二行 ???????</Text> ???????<Text style={styles.instructions}> ?????????totalWidth = {totalWidth} ???????????????????????????//需要修改的第三行 ?????????????????</Text> ?????</View> ???); ?}}const styles = StyleSheet.create({ ?container: { ???flex: 1, ???justifyContent: ‘center‘, ???alignItems: ‘center‘, ???backgroundColor: ‘#F5FCFF‘, ?}, ?welcome: { ???fontSize: 20, ???textAlign: ‘center‘, ???margin: 10, ?}, ?instructions: { ???textAlign: ‘center‘, ???color: ‘#333333‘, ???marginBottom: 5, ?},});AppRegistry.registerComponent(‘MyProject8‘, () => MyProject8);