In Objective-C, those aren't named parameters, like you might find in Python, or faked in Ruby or Groovy. They are called 'Keyword Messages'. In your example ab

In Objective-C, those aren't named parameters, like you might find in Python, or faked in Ruby or Groovy. They are called 'Keyword Messages'. In your example above, the method signature is replace:with:options:range:, compared to say a C++ style replaceWithOptionsRange. It's simply a way to interleave arguments in the message send itself, inherited from Smalltalk.