React Native简介

原文地址
这是翻译，删减的的reac native的官方简介，翻译完之后，还是挺失望的，槽点在于，你需要学习更多东西。同时舞动js和oc两种语言，脚踏web和native两套库，才能从容应对开发中的挑战。脸书此举，不过是给web开发者向移动进军提供了桥梁，对于移动开发者，可有可无，未必有很大吸引力。

• React Native - 使用REACT开发世界一流的原生应用.
• 使用JavaScript和React.
• React Native专注于夸平台的开发效率. 一次学习, 夸平台应用.

开始搞React Native

原生 iOS 组件

可以直接使用iOS的原生组件, 这样界面就会和平台上得应用们一致了.

var React = require(‘react-native’);
var { TabBarIOS, NavigatorIOS } = React;
var App = React.createClass({
  render: function() {
    return (
      <TabBarIOS>
        <TabBarIOS.Item title=“React Native” selected={true}>
          <NavigatorIOS initialRoute={{ title: ‘React Native’ }} />
        </TabBarIOS.Item>
      </TabBarIOS>
    );
  },
});

异步执行

JavaScript代码和原生平台之间的操作都是异步的. 这样解码图片, 往磁盘存储文件, 测量文本大小, 计算布局等等都可以再后台运行而不阻塞界面. 这样REACTIVE-NATIVE应用运行流畅, 响应迅速. The communication is also fully serializable, 可以使用Chrome的Web调试工具进行调试.

触摸操作

React Native自建了一套响应系统代替了iOS的响应链系统.

var React = require(‘react-native’);
var { ScrollView, TouchableHighlight, Text } = React;

var TouchDemo = React.createClass({
  render: function() {
    return (
      <ScrollView>
        <TouchableHighlight onPress={() => console.log(‘pressed’)}>
          <Text>Proper Touch Handling</Text>
        </TouchableHighlight>
      </ScrollView>
    );
  },
});

伸缩盒与样式表

React-Native使用伸缩盒以及样式进行界面的布局和渲染

var React = require(‘react-native’);
var { Image, StyleSheet, Text, View } = React;

var ReactNative = React.createClass({
  render: function() {
    return (
      <View style={styles.row}>
        <Image
          source={{uri: ‘http://facebook.github.io/react/img/logo_og.png'}}
          style={styles.image}
        />
        <View style={styles.text}>
          <Text style={styles.title}>
            React Native
          </Text>
          <Text style={styles.subtitle}>
            Build high quality mobile apps using React
          </Text>
        </View>
      </View>
    );
  },
});
var styles = StyleSheet.create({
  row: { flexDirection: ‘row’, margin: 40 },
  image: { width: 40, height: 40, marginRight: 10 },
  text: { flex: 1, justifyContent: ‘center’},
  title: { fontSize: 11, fontWeight: ‘bold’ },
  subtitle: { fontSize: 10 },
});

其他

React Native 聚焦于iOS的界面开发，其他方面，使用js等web通用技术.

var React = require(‘react-native’);
var { Text } = React;

var GeoInfo = React.createClass({
  getInitialState: function() {
    return { position: ‘unknown’ };
  },
  componentDidMount: function() {
    navigator.geolocation.getCurrentPosition(
      (position) => this.setState({position}),
      (error) => console.error(error)
    );
  },
  render: function() {
    return (
      <Text>
        Position: {JSON.stringify(this.state.position)}
      </Text>
    );
  },
});

扩展能力

可以将原生的代码，导出给js用。

RCT_EXPORT_MODULE();.

// Objective-C

#import “RCTBridgeModule.h”

@interface MyCustomModule : NSObject <RCTBridgeModule>
@end

@implementation MyCustomModule

RCT_EXPORT_MODULE();

// Available as NativeModules.MyCustomModule.processString
RCT_EXPORT_METHOD(processString:(NSString *)input callback:(RCTResponseSenderBlock)callback)
{
  callback(@[[input stringByReplacingOccurrencesOfString:@“Goodbye” withString:@“Hello”]]);
}
@end

// JavaScript

var React = require(‘react-native’);
var { NativeModules, Text } = React;

var Message = React.createClass({
  render: function() {
    getInitialState() {
      return { text: ‘Goodbye World.’ };
    },
    componentDidMount() {
      NativeModules.MyCustomModule.processString(this.state.text, (text) => {
        this.setState({text});
      });
    },
    return (
      <Text>{this.state.text}</Text>
    );
  },
});

Custom iOS views can be exposed by subclassing RCTViewManager, implementing a -(UIView *)view method, and exporting properties with the RCT_EXPORT_VIEW_PROPERTY macro. Then a simple JavaScript file connects the dots.

// Objective-C

#import “RCTViewManager.h”

@interface MyCustomViewManager : RCTViewManager
@end

@implementation MyCustomViewManager

- (UIView *)view
{
  return [[MyCustomView alloc] init];
}

RCT_EXPORT_VIEW_PROPERTY(myCustomProperty);
@end
// JavaScript

var React = require(‘react-native’);
var { requireNativeComponent } = React;

class MyCustomView extends React.Component {
  render() {
    return <NativeMyCustomView {…this.props} />;
  }
}
MyCustomView.propTypes = {
  myCustomProperty: React.PropTypes.oneOf([‘a’, ‘b’]),
};

var NativeMyCustomView = requireNativeComponent(‘MyCustomView’, MyCustomView);
module.exports = MyCustomView;