NSString is exactly the same as CFString?

Question

O'Reilly's Programming iOS 5 says (maybe in a looser sense), that "an NSString is a CFString". But is it true that at least NSString * will point to some memory chunk with an isa, while CFStringRef probably does not?

Answer 1

Not exactly the same; they are Toll-Free Bridged. This Apple Doc should explain in more detail.

Here is even more detail from iOS 5 Programming Pushing The Limits on Google Books.