选中Storyboard上的指定ViewController，设置identity inspector（身份检查器）中的 Storyboard ID 值。
// HQLLoginViewController *loginViewController = [[HQLLoginViewController alloc] init];
// [self.navigationController pushViewController:loginViewController animated:YES];
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:[NSBundle mainBundle]];
HQLLoginViewController *loginViewController = [storyboard instantiateViewControllerWithIdentifier:@"loginViewController"];
[self.navigationController pushViewController:loginViewController animated:YES];
跳转到 Segue 连接的下一个视图控制器：
[self performSegueWithIdentifier:@"ID_step2" sender:self];
