Erm, not true. For example, NSString's
+ (id)stringWithFormat:(NSString *)format, ... + (NSString) stringWithFormat: (NSString *) format, ... {
NSString *string;
va_list ap;
/* Fetch the arguments */
va_start(ap, format);
// Could iterate over the arguments yourself here, or just use:
CFStringRef cfString = CFStringCreateWithFormatAndArguments(NULL, NULL, (CFStringRef)format, args);
string = [NSMakeCollectable(cfString) autorelease];
va_end(ap);
return string;
}