遇到这个 NSString Addition,我不知道它的作用或用途是什么?
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
}