如何在Swift中將類作為參數傳遞給函數？

Question

讓我們考慮一下我有兩個不同的班級。

class A {
var something = "Hello"
}

class B {
var something = "World"
}

現在

class C {

func request() {

    //Call with class A or B it can contain any class. I can call either class A or B depending on condition
    update(myClass: A or B)
}

func update(myClass:A or B ) {
    print(myClass.something) //Since both class have same varaible var something so this code should work either i pass class A or B through function
}

}

請使用Swift幫助我實現這一目標

Answer 1

您不能在Swift中聲明一個可以接受幾種不同類型的輸入參數的函數，因此您不能將類型聲明為A or B 但是，您實際上不需要此來解決您的特定問題。

由於要訪問兩個類實例的公共屬性，因此應在協議中聲明該屬性，使兩個類均符合該協議，然后使該函數采用協議類型的輸入參數。

protocol SomethingProtocol {
    var something: String { get }
}

class A: SomethingProtocol {
    let something = "Hello"
}

class B: SomethingProtocol {
    let something = "World"
}

class C {
    func request() {
        //Call with class A or B it can contain any class. I can call either class A or B depending on condition
        update(something: A())
        update(something: B())
    }

    func update(something: SomethingProtocol) {
        print(something.something) //Since both class have same varaible var something so this code should work either i pass class A or B through function
    }

}

Answer 2

使用協議

protocol MyProtocol: class {
    var something: String { get set }
}

class A: MyProtocol {
    var something = "Hello"
}

class B: MyProtocol {
    var something = "world"
}

class C {
    func update(myClass:MyProtocol ) {
        print(myClass.something) //Since both class have same varaible var something so this code should work either i pass class A or B through function
    }
}

用法：

let a = A()
let b = B()
let c = C()

print(c.update(myClass: a))

print(c.update(myClass: b))

輸出：

你好

世界

Answer 3

創建A和B都符合的協議，並將其用作update（）中的參數類型

protocol SomeProtocol {
    var something: String {get set}
}

func update(_ o: SomeProtocol) {
    print(o.something)
}

Answer 4

眾所周知，我認為使用protocol是最能解決您問題的最干凈的方法。

但是， 可以使用Any傳遞任何對象作為參數，這將需要檢查update方法中要處理的類。

像這樣

class C {
    func update(myClass: Any) {
        if let a = myClass as? A {
            print(a.something)
        }
        if let b = myClass as? B {
            print(b.something)
        }
    }
}

switch可能會更整潔- 參考

class C {
    func update(myClass: Any) {
        switch myClass {
        case let a as A:
            print(a.something)
        case let b as B:
            print(b.something)
        default:
            print("not a thing")
        }
    }
}