卸载 ：
方法1：
step1
$ gem list
cocoapods (0.35.0, 0.34.1, 0.34.0)
cocoapods-core (0.35.0, 0.34.1, 0.34.0)
cocoapods-downloader (0.8.0, 0.7.2)
cocoapods-plugins (0.3.2)
cocoapods-trunk (0.4.1, 0.2.0)
cocoapods-try (0.4.2)
移除程序包
step2
$ sudo gem uninstall cocoapods -v 0.35.0
Successfully uninstalled cocoapods-0.35.0
step3
$ sudo gem uninstall cocoapods-core -v 0.35.0
Successfully uninstalled cocoapods-core-0.35.0
然后安装指定版本的Cocoapods
$ sudo gem install cocoapods -v 0.34.4
$ pod --version
0.34.1
方法2
直接移除组件的方法 从新安装，打包时有问题，暂时没找到原因
$ which pod
$ sudo rm -rf <path>
安装 ：
1.切换源 :
$ gem sources --remove https://rubygems.org/
//等有反应之后再敲入以下命令
$ gem sources -a https://ruby.taobao.org/
$ gem sources -l 查看 并确保只有 https://ruby.taobao.org/2.安装:
sudo gem install cocoapods