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Editorial Team
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Asked: 2026-06-05T08:08:15+00:00

For all intents and purposes, an Objective-C method declaration is simply a C function

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For all intents and purposes, an Objective-C method declaration is
simply a C function that prepends two additional parameters (see
“Messaging” in the Objective-C Runtime Programming Guide ).
Thus, the structure of an Objective-C method declaration differs from the structure of a method that uses named or keyword parameters
in a language like Python, as the following Python example
illustrates:
In this Python example, Thing and NeatMode might be omitted or might have different values when called.

def func(a, b, NeatMode=SuperNeat, Thing=DefaultThing):
    pass

What’s the goal of showing this example on an Objective-c related book?

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1 Answer

  1. Editorial Team

    This is a (poor) example of how Objective-C does not support certain features that other languages, (for example, Python) may. The text explains that while Objective-C has “named parameters” of the format

    - (void)myMethodWithArgument:(NSObject *)argument andArgument:(NSObject *)another;

    Those parameters do not support defaults values, which Python does.

    The mention of prepending two arguments hints at how message passing in Objective-C works under the hood, which is by prepending each method with a receiver object and a selector. You don’t need to know this detail in order to write code in Objective-C, especially at a beginner level, but Apple explains this process here.

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