Question

In Objective-C, if I override a class method using a category, is there a way I can call the original method (the one that was overridden)?

Answer 1

I present you with three icky ways to do this in +(void)load. In every case, name your method MyCategory_method or so.

• class_getMethodImplementation() and class_replaceMethod(). Store the old IMP, and call it directly. You need to get the method’s type encoding. Note that you can just use a normal C function too…
• class_getInstanceMethod(), method_getImplementation(), method_setImplementation(). As above, but you don’t need to get the method’s type encoding.
• class_getInstanceMethod() on both methods, and then method_exchangeImplementations(). Call MyCategory_method to get the original implementation. This is the easiest way to do it.

Sometimes, it’s the only reasonably easy way to make it do what you want…

EDIT: And only do this if you know what you’re doing!