如何在“纯” Swift中创建弱协议引用（不带@objc）

问题描述

弱引用在Swift中似乎不起作用，除非将协议声明为 @objc ，我不想在纯Swift应用程序中使用它。

weak references don't seem to work in Swift unless a protocol is declared as @objc, which I don't want in a pure Swift app.

此代码给出了编译错误（弱不能应用于非类类型 MyClassDelegate ）：

This code gives a compile error (weak cannot be applied to non-class type MyClassDelegate):

class MyClass {
  weak var delegate: MyClassDelegate?
}

protocol MyClassDelegate {
}

我需要在协议前加上 @objc 前缀，然后它才能起作用。

I need to prefix the protocol with @objc, then it works.

问题：什么是纯快速完成弱 委托？

Question: What is the 'pure' Swift way to accomplish a weak delegate?

推荐答案

您需要将协议的类型声明为 AnyObject 。

You need to declare the type of the protocol as AnyObject.

protocol ProtocolNameDelegate: AnyObject {
    // Protocol stuff goes here
}

class SomeClass {
    weak var delegate: ProtocolNameDelegate?
}

使用 AnyObject 您说只有类才能符合此协议，而结构或枚举则不能。

Using AnyObject you say that only classes can conform to this protocol, whereas structs or enums can't.

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