objective c - Obj-C: [NSString stringWithString:@"string"] vs. @"string"

Question

I've seen people do something like [NSString stringWithString:@"some string"]. Why not just do @"some string"?

For an example, look at the facebook-ios-sdk.

+[NSString stringWithString:] -- what's the point? is a similar question, but none of the answers address [NSString stringWithString:@"some string"] vs. @"some string".

Answer 1

Actually there is no difference. [NSString stringWithString: str] just does nothing and returns str if str is immutable already.