DeviceN & Separation color space

Though cocoa is able to display PDFs that contain colors of DeviceN or separation color spaces you cannot create those spaces programatically.
That means, you cannot create instances of colors using DeviceN or separation color spaces. And finally there is a lack of support for other color related stuff like 'overprint black' and others we'd need to create professional PDFs.
Remember that all this depends on underlying Quartz graphics engine.
So new color features first have to be added to Quartz before propagated to Cocoa.

BUT: Take a look at spot color picker for OSX.
It manages to add spot colors to documents of any app that supports OSX color picker.
So how is this possible?!
Hint: This color picker lists instances of NSColor of a dummy gray color space marked by a special ICC profile containing the needed additional information about the spot color. Then it hooks into the PDF/PS generation process and appends additional objects to the generated PDF using the data taken from the ICC profile. This hook only works with spot color picker installed.
So if you hand over a document with spot colors to someone who hasn't installed spot picker you won't get the correct results when printing it to PDF.
This is the most intelligent Cocoa/Quartz hack I have ever seen. Cool stuff.