系统升级到最新的sierra后，执行pod update 失败：
zcj-macair:qinmi alex$ pod update -bash: /usr/local/bin/pod: /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby: bad interpreter: No such file or directory zcj-macair:qinmi alex$ brew install ryby Updating Homebrew... ==> Using the sandbox xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun Error: git cannot be built with any available compilers. Install GNU's GCC brew install gcc Error: Git must be installed and in your PATH! Error: No available formula with the name "ryby" ==> Searching for similarly named formulae... Error: No similarly named formulae found. ==> Searching taps... Error: No formulae found in taps.
按照提示安装对应的程序时，进一步提示错误，发现是xcrun错误。
更新xcrun环境：xcode-select --install
更新ruby：brew install ruby
更新pod：gem install cocoapods