[!] CocoaPods was not able to update the `master` repo...

输入pod install之后出现:

[!] 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`

解决方法：清除CocoaPods缓存后重新执行pod install, 命令如下：

sudo rm -fr ~/.cocoapods/repos/master
pod install