Objective-C equivalent of "override" in C#

Question

Assume a class Vehicle has a method called "StartEngine", and in my subclass called "Airplane" I want to override "StartEngine". If I use C#, I should use the "override" keyword in Airplane's StartEngine method declaration/definition.

The reason I am asking, is that if instead of "StartEngine" I type "startengine", C# will complain, but Objective-C won't, thanks to that keyword.

Answer 1

Yep - it's definitely possible. There's no override keyword though. Just declare a function with an identical signature in your subclass, and it will be called instead of the superclasses version.

Here's what Airplane's startEngine method might look like:

- (void)startEngine
{
    // custom code

    // call through to parent class implementation, if you want
    [super startEngine];
}

Answer 2

All class and instance methods in Objective-C are dispatched dynamically and can be overridden in subclasses. There is nothing like C#'s override keyword, or like its virtual keyword.

Answer 3

All methods in Objective-C are overrideable, you just write a method for the same signature.