detect file creation in a given directory

dispatch_source_t cookitSourceWithFile(const char *cookieFileName) {
    int fd = open(cookieFileName, O_EVTONLY);
    if (fd == -1) {
        return NULL;
    }
    fcntl(fd, F_SETFL, O_NONBLOCK);
    dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_VNODE, fd,DISPATCH_VNODE_DELETE | DISPATCH_VNODE_WRITE | DISPATCH_VNODE_EXTEND | DISPATCH_VNODE_RENAME | DISPATCH_VNODE_REVOKE, DISPATCH_TARGET_QUEUE_DEFAULT);
    if (!source) {
        close(fd);
        return NULL;
    }
    dispatch_source_set_event_handler(source, ^{
        unsigned long const type = dispatch_source_get_data(source);

      switch (type) {
      case DISPATCH_VNODE_WRITE: {
        NSLog(@"目录内容改变!!!");
        break;
      }
      case DISPATCH_VNODE_RENAME: {
        NSLog(@"目录被重命名!!!");
        break;
      }

      default:
        break;
      }
    });
    dispatch_source_set_cancel_handler(source, ^{
        close((int)dispatch_source_get_handle(source));
    });
    dispatch_resume(source);
    return source;
}

    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) firstObject];
    NSString *cookieFile = [documentsDirectory stringByAppendingPathComponent:@"Cookies/"];
    self.source = cookitSourceWithFile([cookieFile UTF8String]);