xcrun: error: active developer path ("/Volumes/Xcode/Xcode6-Beta.app/Contents/Developer") does not exist, use xcode-select to change
After googled, i found the solution.
sudo xcode-select --switch /Applications/Xcode.app
source from : http://www.cnblogs.com/davidhhuan/p/3834446.html
原文：http://www.cnblogs.com/Jim-william/p/4656816.html