在iOS项目中嵌入RN代码

1：在项目跟目录下创建一个ReactComponent文件夹。目录结构如下：

2: 在ReactComponent文件夹下新建一个 package.json 文件

{
  "name": "yy", // 项目名称
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "node node_modules/react-native/local-cli/cli.js start",
    "test": "jest"
  },
  "dependencies": {
    "react": "16.8.3",
    "react-native": "0.59.9"
  },
  "devDependencies": {
    "@babel/core": "7.4.5",
    "@babel/runtime": "7.4.5",
    "babel-jest": "24.8.0",
    "jest": "24.8.0",
    "metro-react-native-babel-preset": "0.54.1",
    "react-test-renderer": "16.8.3"
  },
  "jest": {
    "preset": "react-native"
  }
}

3：到ReactComponent目录下，初始化package.json文件,会生成需要的 node_modules 目录结构如下

// 到对应的目录中
cd xxx/ReactComponent
// 初始化 package.json
npm install 

4：在ReactComponent文件夹下生成 index.ios.js 文件

/*
*
* Sample React Native App
* jff
*
*/

import React, {Component} from 'react';
import {
    AppRegistry,
    StyleSheet,
    Text,
    View,
} from 'react-native';

class NativeRnApp extends Component {
    render(){
        return (
            <View style={styles.container}>
                <Text style={styles.welcome}> Welcome 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>
        );
    }
}

const styles = StyleSheet.create({
    container:{
        flex:1,
        justifyContent:'center',
        alignItems:'center',
        backgroundColor:'#F5FCFF',
    },
    welcome:{
        fontSize:20,
        textAlign:'center',
        margin:10,
    },
    instructions:{
        textAlign:'center',
        marginBottom:10,
        color:'#333333'
    }
})
// 注册组件
AppRegistry.registerComponent('rn', ()=>NativeRnApp);

5：常见Podfile 文件导入yoga，react框架，Podfile文件内容

# 如果导入react-navigation 和 react-native-gesture-handler 需要在Podfile中导入RNGestureHandler 否则会报 null is not an object (evaluating '_rngeasturhandlemodule.default.direction'
# RCTLinkingIOS 用于链接原生module 否则会报 Native Moudle is NULL
# RCTAnimation 导入动画，否则会有警告
# DevSupport 用于调试支持
platform :ios, '9.0'

target 'iOSRN' do
    pod 'yoga', :path => './ReactComponent/node_modules/react-native/ReactCommon/yoga'
    pod 'React', :path => './ReactComponent/node_modules/react-native', :subspecs => [
        'Core',
        'DevSupport',
        'CxxBridge',
        'RCTActionSheet',
        'RCTGeolocation',
        'RCTImage',
        'RCTNetwork',
        'RCTPushNotification',
        'RCTSettings',
        'RCTText',
        'RCTVibration',
        'RCTWebSocket',
        'RCTLinkingIOS',
        'RCTAnimation'
    ]
    pod 'RNGestureHandler', :path => './ReactComponent/node_modules/react-native-gesture-handler'
    pod 'DoubleConversion', :podspec => './ReactComponent/node_modules/react-native/third-party-podspecs/DoubleConversion.podspec'
    pod 'glog', :podspec => './ReactComponent/node_modules/react-native/third-party-podspecs/glog.podspec'
    pod 'Folly', :podspec => './ReactComponent/node_modules/react-native/third-party-podspecs/Folly.podspec'
end

在第一次 pod install 的时候，要打开VPN不然下载不下来 ‘boost-for-react-native’会报错:RPC failed; curl 56 LibreSSL SSL_read: SSL_ERROR_SYSCALL, errno 60 fatal:

如果报‘ios folly/portability.h' file not found’ 需要导入上面的‘:podspec’对应的依赖库，同时为了正常的链接好需要有 'CxxBridge'

6: 在pod install 成功之后，打开 xx.xcworkspace, 之后 file -> Workspace Settings -> 更改“new Build System(Default)”为“legacy Build System”,如下

在info.plist文件中添加"App Transport Security Settings"

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsArbitraryLoads</key>
    <true/>
</dict>

7：生成需要使用的RN文件。让ReactViewController继承自UIVIewController

//
//  ReactViewController.h
//  yy
//
//  Created by jisa on 2019/6/24.
//  Copyright © 2019 jff. All rights reserved.
//

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@interface ReactViewController : UIViewController

@end

NS_ASSUME_NONNULL_END

//
//  ReactViewController.m
//  yy
//
//  Created by jisa on 2019/6/24.
//  Copyright © 2019 jff. All rights reserved.
//

#import "ReactViewController.h"
// 导入需要的组件
#import <React/RCTRootView.h>

@interface ReactViewController ()

@end

@implementation ReactViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Do any additional setup after loading the view. local
    NSString * strUrl = @"http://localhost:8081/index.ios.bundle?platform=ios&dev=true";
    NSURL * jsCodeLocation = [NSURL URLWithString:strUrl];

    RCTRootView * rootView = [[RCTRootView alloc] initWithBundleURL:jsCodeLocation
                                                         moduleName:@"rn"
                                                  initialProperties:nil
                                                      launchOptions:nil];
    self.view = rootView;
}
@end

在进行真机调试是要把localhost换成电脑上的IP地址，同事要保证电脑和手机处于同一网段下。