如何在运行时替换 Objective-C 2.0 类方法实现 [英] How to replace Objective-C 2.0 class method implementation in runtime

问题描述

我使用过 class_replaceMethod 函数，它适用于实例方法，但它不适用于类方法替换.

I have used class_replaceMethod function and it works good with instance methods, but I it doesn't work with class method replacement.

有没有人知道为什么以及我应该怎么做来替换类方法的实现?

Has anybody idea why and what should I do to replace class method implementation?

推荐答案

如果你有一个 Class(我们称之为 MyClass)，那么你必须得到它的元类对类方法进行操作.

If you have a Class (we'll call it MyClass), then you have to get its meta class to operate on class methods.

换句话说:

Class myClass = [MyClass class];
unsigned int numInstanceMethods = 0;
Method * instanceMethods = class_copyMethodList(myClass, &numInstanceMethods);
//instanceMethods is an array of all instance methods for MyClass

Class myMetaClass = objc_getMetaClass(class_getName(myClass));
unsigned int numClassMethods = 0;
Method * classMethods = class_copyMethodList(myMetaClass, &numClassMethods);
//classMethods is an array of all class methods for MyClass

基本上，类用于操作实例级的东西，而元类用于操作类级的东西.

Basically, the class is for operating on instance-level stuff, and the meta class is for operating on class-level stuff.

希望这足以帮助您找出从这里开始的地方.:)

Hopefully this is enough to help you figure out where to go from here. :)

更多有用的信息:http://www.sealiesoftware.com/blog/archive/2009/04/14/objc_explain_Classes_and_metaclasses.html

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