objc:can-invoke-p

(objc:can-invoke-p class-or-object-pointer method)

Whether the receiver has method: t or nil. A string names a class and asks about its class methods. 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.

CL-USER> (objc:can-invoke-p *s* "length")
T
CL-USER> (objc:can-invoke-p *s* "frame")
NIL