如何添加“加载更多”表格视图选项

Question

我的应用程序有一个由 Sqlite DB 填充的表，其中包含大量数据 所以它会导致表视图中的延迟加载

代码，以便我的表视图在特定的限制时间内从 sqlite DB 加载记录

- (void) searchData {
    //i=0;
    [newSearchBar setShowsCancelButton:YES animated:YES];



    NSLog(@"search data started ");

     NSLog(@" checking value %@",newSearchBar.text);
    NSString *databaseName = @"imeating.sql";
    NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES);
    NSString *documentsDir=[documentPaths objectAtIndex:0];
    NSString *databasePath=[documentsDir stringByAppendingPathComponent:databaseName];
    sqlite3 *database;

    if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK)
    {
        NSLog(@"with in if sqlite3 open");
        // Setup the SQL Statement and compile it for faster access
        sqlite3_stmt *compiledStatement ;
        const char *sqlStatement ;

        /* if ([searchFlag isEqualToString:@"DEF"])
         {
         sqlStatement = "select subitem_name, subitem_detail_id from subitem_detail limit 200" ;
         }
         else
         {*/
        sqlStatement = "select category_id, upper(subitem_name), subitem_detail_id, protein, carbohydrates, fat, calorie from subitem_detail where subitem_name LIKE ? order by subitem_name limit ?,?" ;
       NSLog(@"inside search b4 wildsearch %@",searchString);

        wildSearch = [NSString stringWithFormat:@"%@%@",searchString, @"%"];

        NSLog(@"wildsearch %@",wildSearch);

        [newSearchBar setShowsCancelButton:YES animated:YES];
        //NSLog(@"inside search : %@", wildSearch);


        //}

        if (sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) 
        {

             NSLog(@"with in if sqlite3 prepare v2");
            // if (![searchFlag isEqualToString:@"DEF"])
            // {
            sqlite3_bind_text(compiledStatement, 1, [wildSearch UTF8String], -1, SQLITE_TRANSIENT);
            sqlite3_bind_int(compiledStatement, 2, llimit);
            sqlite3_bind_int(compiledStatement, 3, ulimit);

            // }
            // Loop through the results and add it to array

            if (llimit <200){
                 NSLog(@"with in if limit < 200");

                itemArray = [[NSMutableArray alloc] init] ;
            }

            while (sqlite3_step(compiledStatement) == SQLITE_ROW) {

                //NSLog(@" while sqlite3 step");

                NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init] ;
                //[itemDic release];
                //itemDic = nil ;
                itemDic = [[[NSMutableDictionary alloc] init] autorelease];


                NSString *categoryId = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 0)];
                NSString *itemName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 1)];
                NSString *itemId = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 2)];
                NSString *protein = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 3)];
                NSString *carbo = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 4)];
                NSString *fat = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 5)];
                NSString *calorie = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 6)];

                /* NSLog(@"itemname : %@", itemName);
                 NSLog(@"itemid : %@", itemId);
                 NSLog(@"\n");*/

                [itemDic setObject:categoryId forKey:@"categoryId"];
                [itemDic setObject:itemId forKey:@"itemId"];
                [itemDic setObject:itemName forKey:@"itemName"];
                [itemDic setObject:protein forKey:@"protein"];
                [itemDic setObject:carbo forKey:@"carbohydrate"];
                [itemDic setObject:fat forKey:@"fat"];
                [itemDic setObject:calorie forKey:@"calorie"];

                [itemArray addObject:itemDic];
                if (ulimit%200 == 0)
                {
                    //activity = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActionSheetStyleDefault];
                    //[activity startAnimating];
                    [newTableView reloadData];
                    //[newSearchBar setShowsCancelButton:YES animated:YES];
                    //NSLog(@"list all views after 1st reload: %@", [self.navigationController.viewControllers description]);
                    //[newTableView addSubview:activity];
                    //[activity stopAnimating];
                    //[activity release];
                    //NSLog(@" with in if");
                }
                [pool drain];
            } /*else
               {
               UIAlertView *alert = [[UIAlertView alloc ] initWithTitle:@"Error" message:@"sqlite rows not returned" delegate:self cancelButtonTitle:@"OK" otherButtonTitles: nil] ;
               [alert show];
               }*/


        }
    } else
    {
        UIAlertView *alert = [[UIAlertView alloc ] initWithTitle:@"Error" message:@"DataBase Path doesn't exists" delegate:self cancelButtonTitle:@"OK" otherButtonTitles: nil] ;
        [alert show];
    }

    //NSLog(@"itemArray desc : %@",[itemArray description]);

}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    //NSLog(@"Inside number of sections in tableview");
    return 1;

}

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

}

// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
    }

    //NSLog(@"indexpath row val : %d", indexPath.row);

    tableIndex = indexPath ;

    //NSLog(@"print indexpath row : %d", indexPath.row);
    //NSLog(@"print limit : %d", limit);

    if (indexPath.row > limit)
    {
        llimit = llimit+200 ;
        ulimit = ulimit+200 ;

        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

        //[opq cancelAllOperations];
        NSLog(@"before ns operation");

        opq = [NSOperationQueue new];
        //opq = [[NSOperationQueue alloc] init];
        //[opq setMaxConcurrentOperationCount:2];

        // [self performSelectorOnMainThread:@selector(searchData) withObject:nil waitUntilDone:YES];

        NSInvocationOperation *op = [[[NSInvocationOperation alloc] initWithTarget:self selector:@selector(searchData) object:nil] autorelease];



        [opq addOperation:op];

        NSLog(@"after ns operation");
        //[op release];
        //[opq release];

        [pool drain];
        i++;
        limit = limit + 120 ;
        NSLog(@"i=%d",i);

        //[cell setText:[[itemArray objectAtIndex:indexPath.row] valueForKey:@"itemName"]];
    }

    // Configure the cell.
    //[cell setText:[[itemArray objectAtIndex:indexPath.row] valueForKey:@"itemName"]];
    cell.textLabel.text = [[itemArray objectAtIndex:indexPath.row] valueForKey:@"itemName"] ;
    NSString *pval, *cval, *fval, *cal ;
    if ([[[itemArray objectAtIndex:indexPath.row] valueForKey:@"protein"] length] <= 5)
         pval = [[itemArray objectAtIndex:indexPath.row] valueForKey:@"protein"];
    else
        pval = [[[itemArray objectAtIndex:indexPath.row] valueForKey:@"protein"] substringWithRange:NSMakeRange(0, 5)];

    if ([[[itemArray objectAtIndex:indexPath.row] valueForKey:@"carbohydrate"] length] <= 5)
        cval = [[itemArray objectAtIndex:indexPath.row] valueForKey:@"carbohydrate"];
    else
        cval = [[[itemArray objectAtIndex:indexPath.row] valueForKey:@"carbohydrate"] substringWithRange:NSMakeRange(0, 5)];

    if ([[[itemArray objectAtIndex:indexPath.row] valueForKey:@"fat"] length] <= 5)
        fval = [[itemArray objectAtIndex:indexPath.row] valueForKey:@"fat"];
    else
        fval = [[[itemArray objectAtIndex:indexPath.row] valueForKey:@"fat"] substringWithRange:NSMakeRange(0, 5)];

    if ([[[itemArray objectAtIndex:indexPath.row] valueForKey:@"calorie"] length] <= 5)
        cal = [[itemArray objectAtIndex:indexPath.row] valueForKey:@"calorie"];
    else
        cal = [[[itemArray objectAtIndex:indexPath.row] valueForKey:@"calorie"] substringWithRange:NSMakeRange(0, 5)];

    cell.detailTextLabel.text = 
    [NSString stringWithFormat:@"Prot: %@ Carb: %@ Fat: %@ Cal: %@", pval, cval, fval, cal] ;
    return cell;
}

这是我需要在行中“加载更多”按钮的

Answer 1

将部分中的行数添加 + 1：

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [itemArray count] + 1;

}

• 然后在 cellforrowatindexpath 中，查看 indexPath.row 是否大于 [itemArray count]。如果是，则将文本“加载更多...”作为该单元格的标题。

• 在didSelectRowAtIndexPath中，查看indexPath.row是否等于[itemArray count]。如果是这种情况，则向 itemArray 添加 x 个结果，然后调用 [tableView reloadData]。

• 对于某些 UI 改进，您可以在表视图顶部添加 UIActivityIndi​​cator 以显示后台正在进行某些处理。