When editing plist files in Xcode, it can detect the type of plist and show human-readable strings to make it more easy to edit the file. The Info.plist, for example.
Thanks to This question, I found the (or a) place where it stores that structure definition, as InfoPlistStructDefs.xcodeplugin. If I put my own file in there, however, nothing interesting happens. That is, it doesn't show up in the list of possible property list types.
So does anybody know how to make Xcode or the external property list editor application recognize a custom plist structure definition?
I found the answer. I have to put it in
~/Library/Application Support/Developer/Shared/Xcode/Plug-ins/
FYI, PlistEdit Pro also provides a custom interface for creating and editing plist structure definitions, if you don't want to have to mess around with XML.
来源：https://stackoverflow.com/questions/2428768/can-i-create-a-custom-plist-structure-definition