如何将 function 传递给 Swift 中的另一个 class

Question

I need some help passing a function to my second class. I have tried many things but it still not work.

class Main {
    func one() {
        let test = Sub(function: two)
    }
    func two(val: Int, completion: ((Int, String)?)->()) { }
}

class Sub {
    var function: (Int, ((Int, String)?)->())
    init(function: (Int, ((Int, String)?)->())) {
        self.function = function
    }
}

Why is it that i get error on this line

let test = Sub(function: two)

which says: Cannot convert value of type '(Int, ((Int, String)?) -> ()) -> ()' to expected argument type '(Int, ((Int, String)?) -> ())'

What is the reason?

Answer 1

Function has a return value plus the completion, you need to change syntax of function var inisde Sub and the init also

class Main {
    func one() {

        let test = Sub(function: two)
    }
    func two(val: Int, completion: ((Int, String)?)->()) { }
}

class Sub {
    var function: ((Int, ((Int, String)?)->())) -> ()
    init(function:@escaping ((Int, ((Int, String)?)->())) -> ()) {
        self.function = function
    }
}

Answer 2

@escaping need to be added

 class Main {
        func one() {
            let test = Sub(function: two)
        }
        func two(val: Int, completion: (Int, String)?)->() { }
    }

class Sub {
    var function: (Int, (Int, String)?)->()
    init(function: @escaping (Int, (Int, String)?)->()) {
        self.function = function
    }
}