命令行获取XCode的UUID
defaults read /Applications/Xcode.app/Contents/Info DVTPlugInCompatibilityUUID
解决方案:
1. 找到plugin,一般在这个目录下library/Application Support/Developer/Shared/Xcode/Plug-ins
2. 右键点击这个plugin,点"show package contents"
3. 找到info.plist,并且用文本编辑器打开
4. info.plist中搜索DVTPlugInCompatibilityUUIDs
5. 看看是不是缺xcode7的uuid,如果缺就加进去