@class vs. #import

Question

It is to my understanding that one should use a forward-class declaration in the event ClassA needs to include a ClassB header, and ClassB needs to include a ClassA header t

Answer 1

I see a lot of "Do it this way" but I don't see any answers to "Why?"

So: Why should you @class in your header and #import only in your implementation? You're doubling your work by having to @class and #import all the time. Unless you make use of inheritance. In which case you'll be #importing multiple times for a single @class. Then you have to remember to remove from multiple different files if you suddenly decide you don't need access to a declaration anymore.

Importing the same file multiple times isn't an issue because of the nature of #import. Compiling performance isn't really an issue either. If it were, we wouldn't be #importing Cocoa/Cocoa.h or the like in pretty much every header file we have.