isEqual: vs. isEqualToString: vs. compare:
The conclusion I draw at this point is that your choice of
isEqual:andisEqualToString:is purely stylistic. If you have a lot ofisEqual:calls in a method comparing other objects, go ahead and useisEqual:. If you want to tell the reader that you’re only expecting strings to be involved, useisEqualToString:. I believe that the demonstrated corner case makes any safety benefits moot in choosing which method to use.
The main point I would emphasize is the need to check for nil before using compare:, because if the receiver is nil you’ll always get NSOrderedSame. I like to use category methods such as mjtCaseInsensitiveIsEqual: where the result from a nil receiver will be what you expect.
Update (2012-03-30): Dalrymple has a follow-up post.
