Objective-c: How can I require override and not call super?

Question

I guess this is solved by writing a @protocol.

But I'm hungry for knowledge. Is there some flag or other way to require subclasses to override specific methods and not call super? Like the opposite of NS_REQUIRES_SUPER / objc_requires_super?

Answer 1

I do that in code not using any flags.
- I add assertion in the method of the super class that needs to be overridden in case this method is get called

Here I have a class that have a method fetchUserData that should be overridden by the child class

- (void)fetchUserData
{
    NSString *descrip = [NSString stringWithFormat:@"child implementation for method:%@ :  %@",NSStringFromSelector(_cmd),  NSStringFromClass([self class])
    NSAssert(NO, descrip);
}

Answer 2

If I understand this right you're essentially asking how to make an abstract class... forcing subclasses to implement methods.

Check out : Creating an abstract class in Objective-C

In short, have the method throw an exception.

Answer 3

There are some things here that should be useful.

Specifically subclassResponsibility:

EDIT: Good point in the comments - GNUStep != Foundation. In other words, the methods on the page I linked to should be used with caution. However, I've personally used subclassResponsibility: and it works.