Question

Ran across this NSString Addition and I hav no idea what it does or is used for?

NSString *NSStringWithFormat(NSString *formatString, ...) {
va_list args;
va_start(args, formatString);

NSString *string = [[NSString alloc] initWithFormat:formatString arguments:args];

va_end(args);

#if defined(__has_feature) && __has_feature(objc_arc)
    return string;
#else 
    return [string autorelease];
#endif
}

Answer 1

It’s a C function that lets you do this:

NSString *str = NSStringWithFormat(@"This is a number: %d", someIntValue);

instead of this:

// No ARC
NSString *str = [NSString stringWithFormat:@"This is a number: %d", someIntValue];

or

// With ARC
NSString *str = [[NSString alloc] initWithFormat:@"This is a number: %d", someIntValue];

Seems kind of pointless to me since with or without ARC you can use the “No ARC” code. This C function only saves a few characters.