Why does clang allow an @interface without an @implementation? What does it do?

(Originally from a comment on zneak's answer.).

Objective-C has no concept of an 'abstract method'. When you need one, you pretty much have to choice but to use some hack.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.