react native 0.6支持旧版本依赖，iOS 添加po

关于podspec的介绍
[https://www.jianshu.com/p/1aa1ddcb4e4f]
RN0.6以后的依赖iOS都要用pod安装了 ，有一些以前的库很久没有更新的话就无法使用pod管理 ，比如react-native-jpush（测试例子，如果需要的话请使用极光官方维护的https://github.com/jpush/jpush-react-native)
）。

通过yarn add react-native-jpush后，找到这个库所在的目录，创建react-native-jpush.podspec文件，如下图所示

代码如下

require 'json'

packageJson = JSON.parse(File.read('package.json'))
version = packageJson["version"]
description = packageJson["description"]
homepage = packageJson["homepage"]
license = packageJson["license"]
author = packageJson["author"]
repository = packageJson["repository"]["url"]
iqVersion = version.split('-').first

Pod::Spec.new do |s|
    s.name           = "react-native-jpush"
    s.version        = version
    s.description    = description
    s.homepage       = homepage
    s.summary        = "Exit,close,kill,shutdown app completely for React Native"
    s.license        = license
    s.authors        = author
    s.source         = { :git => repository, :tag => version }
    s.platform       = :ios, "9.0"
    s.preserve_paths = 'README.md', 'package.json', '*.js'
    s.source_files   = 'ios/RCTJPush/**/*.{h,m}'
    s.vendored_libraries = "ios/JPushSDK/*.a"
    s.public_header_files = 'ios/JPushSDK/*.h'
    s.dependency 'React'
end

如果有别的项目可以根据需求更改这个模板，这里主要改的是

s.source_files
s.vendored_libraries
s.public_header_files
三个变量

然后终端进入到iOS目录执行，pod install就可以了