An instance of
standard-objc-object or a class defined by
objc-object-pointer returns the Objective-C foreign pointer associated with a given Lisp object. If object is an instance of standard-objc-object then pointer will have foreign type objc-object-pointer. Otherwise, object should be a class defined by define-objc-class and the associated Objective-C class object is returned as a foreign pointer of type objc-class.
LispWorks Objective-C and Cocoa Interface User Guide and Reference Manual - 15 Feb 2015