CocoaPods解决Unable to add a sourc

原文地址：https://my.oschina.net/jjtm/blog/492083

pod update出现：

[!] Unable to add a source with url `https://github.com/CocoaPods/Specs.git` named `master-1`.

You can try adding it manually in `~/.cocoapods/repos` or via `pod repo add`.

这样的提示。

解决办法：由于装了多个Xcode，在终端输入：sudo xcode-select -switch /Applications/Xcode8.0.app