打开terminal,输入如下命令:
find ~/Library/Application Support/Developer/Shared/Xcode/Plug-ins -name Info.plist -maxdepth 3 | xargs -I{} defaults write {} DVTPlugInCompatibilityUUIDs -array-add `defaults read /Applications/Xcode.app/Contents/Info.plist DVTPlugInCompatibilityUUID`
具体原理,详看下面链接
http://joeshang.github.io/2015/04/10/fix-xcode-upgrade-plugin-invalid/