objc:invoke-bool

(objc:invoke-bool class-or-object-pointer method &rest args)

objc:invoke for a method that answers a BOOL: nil for NO, t otherwise. Plain objc:invoke answers 0 or 1 for the same method, as LispWorks does. 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:invoke-bool *s* "hasPrefix:" "hello")
T
CL-USER> (objc:invoke *s* "hasPrefix:" "hello")
1