CocoaPods
执行pod install（update）会假死，卡在Analyzing dependencies
原因在于执行命令的时候会升级CocoaPods的spec仓库，加一个参数可以省略这一步。加参数的命令如下：
pod install --verbose --no-repo-update
pod update --verbose --no-repo-update
命令记录
gem sources --remove https://rubygems.org/
gem sources -a http://ruby.taobao.org/
gem sources -l
gem update --system
gem install cocoapods
gem update cocoa pods
pod list
pod search AFNetworking
pod install
pod update
rm -rf ~/.cocoapods
pod setup
cd ~/.cocoapods
du -sh
platform :ios, '7.0'
pod "AFNetworking", "~> 2.0"