Creating an abstract class in Objective-C

Question

I\'m originally a Java programmer who now works with Objective-C. I\'d like to create an abstract class, but that doesn\'t appear to be possible in Objective-C. Is this poss

Answer 1

In Xcode (using clang etc) I like to use __attribute__((unavailable(...))) to tag the abstract classes so you get an error/warning if you try and use it.

It provides some protection against accidentally using the method.

Example

In the base class @interface tag the "abstract" methods:

- (void)myAbstractMethod:(id)param1 __attribute__((unavailable("You should always override this")));

Taking this one-step further, I create a macro:

#define UnavailableMacro(msg) __attribute__((unavailable(msg)))

This lets you do this:

- (void)myAbstractMethod:(id)param1 UnavailableMacro(@"You should always override this");

Like I said, this is not real compiler protection but it's about as good as your going to get in a language that doesn't support abstract methods.