Working with PDFs in Cocoa

I am wondering if there is a way to us开发者_JAVA技巧e the simpler classes in PDFKit (PDFDocument, PDFPage), and still get references to the lower level CGPDFDocumentRef object. Does anyone know if this is possible?

From PDFDocument.h:

// This is the CGPDFDocument associated with the PDFDocument 
// object.  With this object you can call many CoreGraphics 
// API. May return NULL if the document was not created from 
// an existing PDF file or data.
- (CGPDFDocumentRef) documentRef;