二维数组左滑删除某一行

#pragma mark 编辑操作（删除或添加）
//实现了此方法向左滑动就会显示删除（或添加）图标
-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath{
    
    NTContactGroup * group = _contacts[indexPath.section];
    NTContact * contact = group.contacts[indexPath.row];
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        [group.contacts removeObject:contact];
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationBottom];
        if (group.contacts.count == 0) {
            [_contacts removeObject:group];
            [tableView reloadData];
        }
    }else if (editingStyle == UITableViewCellEditingStyleInsert){
        
        NTContact * addContact = [[NTContact alloc]init];
        addContact.firstName = @"Guan";
        addContact.lastName = @"yu";
        addContact.mobileNumber = @"12345678901";
        [group.contacts insertObject:addContact atIndex:indexPath.row];
        [tableView insertRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationBottom];
    }
}