班级扩展与班级类别 [英] Class extension vs class category

问题描述

类扩展@interface Class ()功能强大得多，可以将变量注入到类中.类别@interface Class (Category)不能.

Class extensions @interface Class () are a lot more powerful and can inject variables into the class. Categories @interface Class (Category) can't.

还有什么其他区别?什么时候应该在类扩展上使用类别?

What other differences are there, and when should one use a category over a class extension?

推荐答案

主要区别在于，通过扩展，编译器将期望您在主@implementation内实现方法，而对于类别，则拥有单独的类别@implementation块.因此，您几乎应该只在主.m文件的顶部使用扩展名(顺便说一句，您应该在这唯一的地方关注ivars)-就是说，是扩展名.

The main difference is that with an extension, the compiler will expect you to implement the methods within your main @implementation, whereas with a category you have a separate @implementation block. So you should pretty much only use an extension at the top of your main .m file (the only place you should care about ivars, incidentally) -- it's meant to be just that, an extension.

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