ios - 在 Swift 中，键值编码是否可用于自定义对象而无需子类化 NSObject？

Question

在Key-Value Coding Programming Guide它声明 NSObject 子类符合 KVC。

Swift objects that inherit from NSObject or one of its subclasses are key-value coding compliant for their properties by default

自定义对象(结构、类)是否可以采用 NSKeyValueCoding 并符合 KVC 标准？另外，如何仅通过子类化 NSObject 将 KVC 赋予对象？

Answer 1

与任何对象在技术上都可以遵守的正式协议(protocol)不同，NSKeyValueCoding 通过Informal Protocols: 可用于任何NSObject

An informal protocol is a category on NSObject, which implicitly makes almost all objects adopters of the protocol. (A category is a language feature that enables you to add methods to a class without subclassing it.) Implementation of the methods in an informal protocol is optional. Before invoking a method, the calling object checks to see whether the target object implements it. Until optional protocol methods were introduced in Objective-C 2.0, informal protocols were essential to the way Foundation and AppKit classes implemented delegation.

这与简单地将 KVC 直接实现到 NSObject 中不同，我认为非正式协议(protocol)的主要好处是将 NSObject 的功能拆分到单独的文件中.但是使用非正式协议(protocol)可能还有其他好处

而且因为 NSKeyValueCoding 是 NSObject 上的一个类别，不幸的是你不能让任何自定义对象都支持 KVC