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,{"
"}
          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,
  StyleSheet,
  Text,
  View,
} = 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);