The function 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.
Note that for a given returned pointer, the value of the form
(objc-object-from-pointer pointer)
standard-objc-object
define-objc-class
objc-object-pointer
objc-class
objc-object-from-pointer
LispWorks Objective-C and Cocoa Interface User Guide and Reference Manual - 21 Mar 2017