objc:with-objc-block

(objc:with-objc-block (var type function) form*)

Evaluates forms with var bound to a block objc:make-objc-block makes from type and function, and frees it on every exit, answering the last form's values. Right for asynchronous work too: a callee that keeps the block holds a copy, which keeps function alive after the form returns. Part of the macOS-only objc package -- the interpreter (java -jar, or the rontolisp native binary), a compiled .class / .jar and a --native executable for macOS on Apple silicon, never a .wasm; on a machine without the runtime it signals an error. See the macOS GUI guide.

MY-APP> (with-objc-block (each '(:void (objc-object-pointer (:unsigned :long-long)
                                        (:pointer objc-c++-bool)))
                               (lambda (word index stop)
                                 (declare (ignore stop))
                                 (format t "~a ~a~%" index (ns-string-to-string word))))
          (invoke *words* "enumerateObjectsUsingBlock:" each))
0 pear
1 fig
2 apple
NIL