ios - 如何在协议(protocol)中声明泛型函数

Question

这是我的代码

protocol sharedFunction {

      func transformDictionary<Element>(postDictionary:[Element:Element], key: Element) -> Element


}


class newUser: sharedFunction {

var email:String?
var username:String?
var uid: String?

func transformDictionary(postDictionary: [String : Any], key: String) -> newUser {

 }
}

但我不断收到此错误“Type newUser”不符合协议(protocol)““sharedFunction”

Answer 1

错误的发生仅仅是因为您的类型不符合消息明确指出的协议(protocol)。我会像这样重写你的代码:

protocol SharedFunction {
    associatedtype Element: Hashable
    func transformDictionary(postDictionary: [Element:Element], key: Element) -> Element
}

class NewUser: SharedFunction {

    typealias Element = Int

    var email: String?
    var username: String?
    var uid: String?

    func transformDictionary(postDictionary: [Element : Element], key: Element) -> Element {
        return 1
    }

}

我不知道这段代码的上下文是什么，所以我不知道我的代码对你是否有意义，但我想你明白了。