Is NSObject(RACSubscribable) necessary?

[jonsterling]

I'm looking at the NSObject(RACSubscribable) category, and it would seem that all of its methods assert conformance to <RACSubscribable> at runtime. Wouldn't this be better placed in the actual <RACSubscribable> protocol? It seems like that would be the safer and more hygienic approach.

Are there some use-cases that make the current approach necessary, or at least more optimal?

[joshaber]

Those are all just conveniences so you don't have to manually create a RACSubscriber all the time. They're all based off <RACSubscribable> methods but since protocols can't have concrete implementations... we're left to implement them as a category.