Info

This is a single header library that exposes a function to hook a method of a specific instance (as opposed to other hooking functions which hook the class itself)

Usage

void hookInstance(id instance, SEL targetSEL, IMP replacementFp, IMP* origFp) 

instance: the instance you want to hook
targetSEL: selector for the method you want to hook
replacementFp: function pointer to the replacement function
origFp: adress of a function pointer that will be filled in with a stub which may be used to call the original implementation. This can be NULL if you don't wish to use original implementation

Using with the same instance multiple times is supported, you can do this to hook multiple methods.

There is an example for the usage in "example" branch, as a tip; it is designed to be similiar with MSHookMessageEx function

How it works

It is creating a new class everytime you call the function, replaces the target method of it and uses object_setClass on the instance with that class to apply the hook