在iOS中下载JSON对象时出现问题

在我的iOS应用程序中，我使用JSON上传MySQL对象

这是CelforRowatineXpath方法：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    Lista_Actividades_TableViewCell *cell =[tableView dequeueReusableCellWithIdentifier:@"Cell"];
    if (cell ==nil){
        cell = [[Lista_Actividades_TableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"Cell"];
    }

    cell.dia_label.hidden = NO;
    cell.minutos_label.hidden = NO;

    cell.hora_label.hidden = NO;
    cell.mes_label.hidden = NO;
     cell.puntos_label.hidden = NO;

    NSString *hora = [[categorias objectAtIndex:indexPath.row] objectForKey:@"hora_evento"];
    NSString *minutos  = [[categorias objectAtIndex:indexPath.row] objectForKey:@"minutos_evento"];


        if ([hora isEqualToString:@"0"]){
            hora = @"00";
        }
        if ([minutos isEqualToString:@"0"]){
            minutos = @"00";



        }


    if ([ [[categorias objectAtIndex:indexPath.row] objectForKey:@"hora_evento"] isEqualToString:@"0"] && [[[categorias objectAtIndex:indexPath.row] objectForKey:@"minutos_evento"] isEqualToString:@"0"]){
        cell.hora_label.hidden = YES;
        cell.puntos_label.hidden = YES;
    }
    else
    {
        cell.hora_label.text = [[categorias objectAtIndex:indexPath.row] objectForKey:@"hora_evento"];
    }
    if ([[[categorias objectAtIndex:indexPath.row] objectForKey:@"hora_evento"] isEqualToString:@"0"] && [[[categorias objectAtIndex:indexPath.row] objectForKey:@"minutos_evento"] isEqualToString:@"0"]){
        cell.minutos_label.hidden = YES;
    }
    else
    {
        cell.minutos_label.text = minutos;
    }





    if ([ [[categorias objectAtIndex:indexPath.row] objectForKey:@"dia_evento"] isEqualToString:@"0"]){
        cell.dia_label.hidden = YES;
    }
    else
    {
         cell.dia_label.text = [[categorias objectAtIndex:indexPath.row] objectForKey:@"dia_evento"];
    }

        NSString *mes_evento = [[categorias objectAtIndex:indexPath.row] objectForKey:@"mes_evento"];
        int value = [mes_evento intValue];





    if ([ [[categorias objectAtIndex:indexPath.row] objectForKey:@"mes_evento"] isEqualToString:@"0"]){
        cell.mes_label.hidden = YES;
    }
    else
    {
        switch (value)
        {
            case 1:
                cell.mes_label.text =@"ENERO";
                break;
            case 2:
                cell.mes_label.text =@"FEBRERO";
                break;
            case 3:
                cell.mes_label.text =@"MARZO";
                break;
            case 4:
                cell.mes_label.text =@"ABRIL";
                break;
            case 5:
                cell.mes_label.text =@"MAYO";
                break;
            case 6:
                cell.mes_label.text =@"JUNIO";
                break;
            case 7:
                cell.mes_label.text =@"JULIO";
                break;
            case 8:
                cell.mes_label.text =@"AGOSTO";
                break;
            case 9:
                cell.mes_label.text =@"SEPTIEMBRE";
                break;
            case 10:
                cell.mes_label.text =@"OCTUBRE";
                break;
            case 11:
                cell.mes_label.text =@"NOVIEMBRE";
                break;
            case 12:
                cell.mes_label.text =@"DICIEMBRE";
                break;
            default:
                cell.mes_label.text =@"SIN MES";
                break;
        }
    }







     cell.titulo_label.text = [[[categorias objectAtIndex:indexPath.row] objectForKey:@"titulo_evento"] uppercaseString];

    NSString *lugar = [[categorias objectAtIndex:indexPath.row] objectForKey:@"lugar_evento"];
    if ([lugar isEqualToString:@"0"]){
        NSLog(@"LUGAR AQUI ES=%@",lugar);
        cell.lugar_label.text = @" ";
    }
    else {
    cell.lugar_label.text = [[categorias objectAtIndex:indexPath.row] objectForKey:@"lugar_evento"];
    }

    NSMutableString *logo = [[NSMutableString alloc]initWithString:@"hidden here"];
    NSString *imageURL = [[categorias objectAtIndex:indexPath.row] objectForKey:@"imagen_evento"];






    if(imageURL != nil && ![imageURL isEqual:[NSNull null]])
    {
        [logo appendString:imageURL];
        NSURL *logoURL = [NSURL URLWithString:logo];
        NSData *logoData = [NSData dataWithContentsOfURL:logoURL];

        cell.imagen_label.image = [UIImage imageWithData:logoData];
    }
    else{
        cell.imagen_label.image = [UIImage imageNamed:@"no_image-512.png"];
    }





    return cell;
}

共有45个对象，并且始终在同一个对象上，应用程序崩溃，出现以下错误：

URL = ACTteatro.jpg
mujergrancanaria(4031,0x4f9e1d4) malloc: *** mach_vm_map(size=8388608) failed (error code=3)
*** error: can't allocate region securely
*** set a breakpoint in malloc_error_break to debug
mujergrancanaria(4031,0x4f9e1d4) malloc: *** mach_vm_map(size=8388608) failed (error code=3)
*** error: can't allocate region securely
*** set a breakpoint in malloc_error_break to debug
libc++abi.dylib: terminating with uncaught exception of type std::bad_alloc: std::bad_alloc

我开发的应用程序可以下载更多的JSON对象、图片和文本，但从未遇到过这个问题

---

欢迎任何帮助。

您应该异步下载图像，并将其保存在object中，然后重新使用

  - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    {
        static NSString *cellIdentifier = @"venue";
        UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:cellIdentifier forIndexPath:indexPath];

        if (!cell) {
            cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellIdentifier];
        }

        Venue *venue = ((Venue * )self.venues[indexPath.row]);
        if (venue.userImage) {
            cell.imageView.image = venue.image;
        } else {
            // set default user image while image is being downloaded
            cell.imageView.image = [UIImage imageNamed:@"batman.png"];

            // download the image asynchronously
            [self downloadImageWithURL:venue.url completionBlock:^(BOOL succeeded, UIImage *image) {
                if (succeeded) {
                    // change the image in the cell
                    cell.imageView.image = image;

                    // cache the image for use later (when scrolling up)
                    venue.image = image;
                }
            }];
        }
    }



    - (void)downloadImageWithURL:(NSURL *)url completionBlock:(void (^)(BOOL succeeded, UIImage *image))completionBlock
    {
        NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
        [NSURLConnection sendAsynchronousRequest:request
                                           queue:[NSOperationQueue mainQueue]
                               completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {
                                   if ( !error )
                                   {
                                        UIImage *image = [[UIImage alloc] initWithData:data];
                                        completionBlock(YES,image);
                                    } else{
                                        completionBlock(NO,nil);
                                    }
                               }];
    }

---

在这里，您正在从Internet下载数据，并将其转换为图像，所有这些都在主线程上：

NSURL *logoURL = [NSURL URLWithString:logo];
NSData *logoData = [NSData dataWithContentsOfURL:logoURL];
cell.imagen_label.image = [UIImage imageWithData:logoData];

---

不要那样做。尽快归还手机。下载并异步处理映像。有很多关于堆栈溢出的问题，展示了各种方法，甚至是专门为您设计的。

在后台任务中下载您的图像，在主线程中执行网络操作会导致严重的问题：

要在后台任务中下载图像，可以执行以下操作：

if(imageURL != nil && ![imageURL isEqual:[NSNull null]])
{
    [logo appendString:imageURL];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
        NSURL *logoURL = [NSURL URLWithString:logo];
        NSData *logoData = [NSData dataWithContentsOfURL:logoURL];
        dispatch_async(dispatch_get_main_queue(), ^{
            if (logoData.length) {
                cell.imagen_label.image = [UIImage imageWithData:logoData];
            }else{
                cell.imagen_label.image = [UIImage imageNamed:@"no_image-512.png"];
            }
        });
    });
}

---

希望这有帮助……：）

尝试使用SDWebImages进行图像上载

谢谢你，我知道，它只是一个知道图像名称的标签…它在NSLog中。好的，你可以在这里共享整个url。url不是问题，直到应用程序崩溃的对象，所有图片都显示出来。我已经删除了行：NSLog（@“url=%@”，imageURL）；问题仍然存在。您是否保存下载的图像并在重新使用cell时再次使用它们？谢谢，我也会尝试Rashad的答案。您是否介意向我解释正确的方法。我的意思是，对于每个对象调用CellForRowatinex方法，这意味着数据放在单元格中，图像从internet下载并放在图像视图容器中，对吗？但是我已经完成了我的代码，负载太高，应用程序崩溃。谢谢你，我还会尝试Rashad的答案。谢谢你Rashasd，实施你的建议会让图像下载更快，但在同一个对象上，应用程序没有崩溃，但停止工作，它冻结。它最终崩溃了…：（与之前相同：mujergrancanaria（4757,0x4fde1d4）malloc:**mach_vm_映射（大小=8388608）失败（错误代码=3）***错误：无法分配区域securely@ModestoVasco>我很确定你的应用程序有内存泄漏。你能监控你使用了多少内存吗？在崩溃瞬间，5.7 Mb