objc:make-objc-block

(objc:make-objc-block type function)

Makes an Objective-C block that calls function, answering an objc:objc-block that passes wherever a method or a C function takes a block. type is (result-type (argument-type*)) in the types objc:invoke's list form takes, or a name objc:define-objc-block-type defined; the block's arguments reach function converted by those types, as a method's reach its body, and its value is converted back. An error inside function is printed and the block answers zero. A block runs on the thread that calls it -- a libdispatch worker for a completion handler -- except in a --native executable, where a void block called on another thread waits for the main thread's event loop (the program's sleep) and a block answering a value there answers zero. Free it with objc:free-objc-block, or make it with objc:with-objc-block; a callee that keeps the block holds a copy, which keeps function alive after the free. 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> (defvar *add* (make-objc-block '(:int (:int :int)) (lambda (a b) (+ a b))))
*ADD*
MY-APP> *add*
#<OBJC:OBJC-BLOCK i@?ii live>
MY-APP> (call-objc-block '(:int (:int :int)) *add* 3 4)
7