从git上pull了一个新分支，新分支的Pods需要删除重新安装下:
执行删除，
rm -rf Pods
执行重装pod,
pod install
然后就受到报错：
Your Podfile requires that the plugin `cocoapods-binary` be installed.
中间试了各种方法：
pod update
pod repo remove master
pod setup
pod install
依然报错，还是对原理不清楚惹的祸，明明就是提示没安装cocoapods-binary嘛，OK, 安装cocoapods-binary:
sudo gem install cocoapods cocoapods-binary
然后在执行pod install就成功了。
参考了：
1.Your Podfile requires that the plugin `cocoapods-keys`
想看个开源库，里面要求用cocoapods-keys，就照着上面的提示
sudo gem install cocoapods cocoapods-keys
