Method swizzling and refinements are basically the same thing. The real difference isn't in the features, it's in the fact that Ruby is a dynamic language, and Obj-C is only dynamically typed. You can swizzle all you want in a statically compiled program, and refinements work equally well in a "static" Ruby program. The problems with refinements start coming to light when you start refining things at runtime, i.e., with module_eval. Obj-C doesn't have this problem, since swizzling happens only once at compile time.