如何将 function 传递给 Swift 中的另一个 class

Question

我需要一些帮助将 function 传递给我的第二个 class。 我已经尝试了很多东西，但它仍然不起作用。

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
    }
}

为什么我在这条线上出错

let test = Sub(function: two)

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

是什么原因？

Answer 1

Function 有一个返回值加上完成，你需要改变function var inisde Sub和init的语法

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 需要添加

 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
    }
}