源码

/** * Sample React Native App * https://github.com/facebook/react-native */
'use strict';

var React = require('react-native');
var {
  AppRegistry,StyleSheet,Text,View,} = React;

var helloworld = React.createClass({
  render: function() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>
          Welcome to React Native!
        </Text>
        <Text style={styles.instructions}>
          To get started,edit index.ios.js
        </Text>
        <Text style={styles.instructions}>
          Press Cmd+R to reload,{'\n'}
          Cmd+D or shake for dev menu
        </Text>
      </View>
    );
  }
});

var 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('hellowrold',() => helloworld);

问题

AppRegistry.registerComponent('hellowrold',() => helloworld);中registerComponent方法的第一个参数hellowrold参数一定要跟项目名一样，否则就会报错。

总结

新建项目分5步：

引入react-native

var React = require('react-native');

定义组件

var { AppRegistry,} = React; 

定义界面控件

var helloworld = React.createClass({});

定义控件样式

var styles = StyleSheet.create({});

为项目注册界面

AppRegistry.registerComponent('项目名',() =>界面);