tabbar隐藏方法（无白条）

SmallClassViewController *smclassVC = [[SmallClassViewController alloc] initWithStyle:(UITableViewStylePlain)];
    smclassVC.title = classification.name;
    smclassVC.classString = urlArray[indexPath.item];
    smclassVC.hidesBottomBarWhenPushed = YES;
    [self.navigationController pushViewController:smclassVC animated:YES];

重要的是smclassVC.hidesBottomBarWhenPushed = YES这一句，十分有效；