How do I attach a Void -> Void closure to a header file in Objective-C

Question

I'm updating a legacy app and I want to add a nullable, assignable closure of type (() -> ())? to my header file. How do I do this in Objective-C?

A closure is called a `block` in Objective-C. See there: http://fuckingblocksyntax.com If it's a method closure see the one there: https://developer.apple.com/documentation/uikit/uiviewcontroller/1621380-presentviewcontroller?language=objc — Larme, Oct 27 '18 at 17:18
Possible duplicate of [Block Declaration Syntax List](https://stackoverflow.com/questions/9201514/block-declaration-syntax-list) — JAL, Oct 27 '18 at 17:50

score 0 · Answer 1 · answered Oct 27 '18 at 18:11

In my .h file, this is what I was going for:

@property (nullable, copy) void (^myNullableClosure) (void);

Then I can assign in my Swift code as:

let vc = ViewController()
vc.myNullableClosure = {
    print("something")
}

then later in the ViewController, I call myNullableClosure?()

1 Answers1