本次cocoapods安装使用Homebrew命令安装
一：安装Homebrew
1、执行安装指令： /bin/zsh -c "$(curl -fsSL https://gitee.com/cunkai/HomebrewCN/raw/master/Homebrew.sh)"
2、验证安装指令：brew -v
二：更换rudy源
1、移除自带源指令： gem sources --remove https://rubygems.org/
2、替换国内源指令： gem sources --add https://gems.ruby-china.com/
3、检查是否更新指令：gem sources -l
三：安装cocoapods
1、执行安装指令：brew install cocoapods
2、pod设置更新命令：pod setup
3、本地库下载指令：git clone https://github.com/CocoaPods/Specs.git ~/.cocoapods/repos/master
4、搜索三方库验证：pod search Alamofire
