如何重新安装 CocoaPods

报错内容有这么一句：

You might have to install separate package for the ruby development environment, ruby-dev or ruby-devel for example.

解决办法：重新安装CocoaPods:

// 删除
sudo rm -rf /Library/Developer/CommandLineTools

// 重装
sudo xcode-select --install

// 切换到Xcode beta版的命令行
sudo xcode-select -switch /Applications/Xcode-beta.app

// 重新安装CocoaPods
sudo gem install -n /usr/local/bin cocoapods

// 设置
pod setup