为什么在Swift中使用仅类协议？ [英] Why use class only protocols in Swift?

问题描述

任何人都可以在Swift中向我解释只有类的协议。我了解协议是什么以及我们使用它们的原因。我也明白，当我们在其中使用引用类型对象时，建议使用仅类协议，并且希望仅将协议构造限制为类。但是，我找不到任何支持该建议的好答案。为什么推荐？在这种情况下使用普通协议有什么缺点。

Can anyone please explain class only protocols to me in Swift. I understand what protocols are and why we use them. I also understand that its recommended to use class only protocols when we use reference type objects in it and want to limit the protocol conformation to classes only. However, I can't find any good answer to support that recommendation. Why is it recommended? What is the drawbacks of using normal protocols in that case.

推荐答案

一个用例：

• 您有一个委托协议，有人希望拥有该协议类型的弱属性。 weak 只能用于引用类型;因此，协议必须是仅限类的。

• You have a "delegate" protocol and someone wants to have a weak property of that protocol type. weak can only be used on reference types; therefore, the protocol must be class-only.

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