[!] CocoaPods was not able to update the `master` repo. If this is an unexpected issue and persis...

执行命令
pod repo update --verbose 后
一直报错：
[!] CocoaPods was not able to update the master repo. If this is an unexpected issue and persists you can inspect it running `pod repo update --verbose

解决方案： 升级 ruby 到最新版本，再执行命令，OK！
升级命令：

brew install ruby