在UITableViewCell里面显示子单元

我想在UITableViewCell里面显示子单元格。我有两个包含groupname和groupid的数组。我能够通过使用下面的代码在具有自定义TableViewCell的tableview中显示组名。在UITableViewCell里面显示子单元

NSArray *groupIdArr; 
    NSArray *groupNameArr; 

groupNameArr (
    ANTISERA, 
    CLIA, 
    COAGULATION, 
    CONFIRMATORY, 
    ELISA, 
    IMMUNOLOGY, 
    MISC, 
    RAPID 
) 

groupIdArr (
    20, 
    21, 
    22, 
    23, 
    19, 
    31, 
    29, 
    18 
) 


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    return [groupIdArr count]; 
} 



- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    static NSString *simpleTableIdentifier = @"ProductGroupTableViewCell"; 

    ProductGroupTableViewCell *cell = (ProductGroupTableViewCell *)[tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier]; 
    if (cell == nil) 
    { 
     NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"ProductGroupTableViewCell" owner:self options:nil]; 
     cell = [nib objectAtIndex:0]; 
    } 

    cell.productGroupNameLbl.text = [groupNameArr objectAtIndex:indexPath.row]; 

    return cell; 
} 

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
     NSString *saveGroupId = [groupIdArr objectAtIndex:indexPath.row]; 

     [[NSUserDefaults standardUserDefaults] setObject:saveGroupId forKey:@"SavedGroupId"]; 
     [[NSUserDefaults standardUserDefaults] synchronize]; 

    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil]; 
    UIViewController *productListVC = [storyboard instantiateViewControllerWithIdentifier:@"ProductsListViewController"]; 
    [self.navigationController pushViewController:productListVC animated:YES]; 


}