Question

I’m trying to work out the pros and cons of @"" and [NSString string] as they appear to behave in a similar fashion. I guess I’m hoping [NSString string] returns a static value thus avoiding unnecessary string creation in memory. Can anyone shed some light as the documentation is inconclusive.

Answer 1

It’s quite probable that @"" == [NSString string] and therefore the decision is just a matter of style. Aha, it’s not:

NSLog(@"%i", @"" == @""); // 1
NSLog(@"%i", [NSString string] == [NSString string]); // 1
NSLog(@"%i", [[NSString string] stringByAppendingString:@"foo"] ==
             [@"" stringByAppendingString:@"foo"]); // 1
NSLog(@"%i", @"" == [NSString string]); // 0

But I can’t think of any use case where the difference would matter.