在执行`
$ xcode-select --install
后出现错误
xcode-select: error: command line tools are already installed, use "Software Update" to install updates
解决办法:
$ rm -rf /Library/Developer/CommandLineTools
$ xcode-select --install
问题完美解决
如果提示权限不够那么加上sudo
参考地址:https://stackoverflow.com/questions/34617452/how-to-update-xcode-from-command-line