Provide the whole quote.
Contains the user’s preferences. You should never create files in this directory yourself. To get or set preference values, you should always use the NSUserDefaults class or an equivalent system-provided interface.
The system provided interface in XDG apps is the XDG path - the Apple code there implies writiing a GUI app as none of the paths it says are not updated by the App ie no manual updates.
This directory contains app-specific preference files. You should not create files in this directory yourself.