SetWindowsHookEx for Mac OS X?

Question

Windows hooks allows you to poke inside other processes and sometimes alter their behaviors.

Is there such thing for Mac OS X?

Thanks!

Answer 1

SetWindowsHookEx is more like the old InputManager hack, in the sense that you change the code of an app from inside a shared library / a plugin loaded to it.

See SIMBL for a ready-made code injector to another process. For Objective-C classes, you then need to use method swizzling. I haven't tried replacing C functions / C++ classes myself, but surely it can be done using mach_override. See also this blog post.

But usually if you want to modify a GUI app, tapping into Objective-C classes would be sufficient.