Iphone 表视图中的图像延迟加载

我想在我的表视图中使用延迟加载图像的概念。我的图像规则字符串数组是（

MSMutableArray

）“图像”。如何在

cellforrowatinexpath

中实现此功能

它看起来像：

-(UITableViewCell *) tableView:(UITableView *)AtableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{

    UITableViewCell *cell=[searchtable dequeueReusableCellWithIdentifier:@"cell"];

    if(!cell)
    {

        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"cell"];



        cell.textLabel.font=[UIFont systemFontOfSize:12];

        cell.imageView.image=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[appSmallLogos objectAtIndex:indexPath.row]]]];

        cell.detailTextLabel.text=[appReleaseDates objectAtIndex:indexPath.row];


    }

    return cell;
}

您可以使用该库，该库将异步下载和缓存映像。通过将url作为参数传递给它

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

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];

    if (cell == nil)
    {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
                                       reuseIdentifier:MyIdentifier] autorelease];
    }

    // Here we use the new provided setImageWithURL: method to load the web image
    [cell.imageView setImageWithURL:[NSURL URLWithString:@"http://www.domain.com/path/to/image.jpg"]
                   placeholderImage:[UIImage imageNamed:@"placeholder.png"]];

    cell.textLabel.text = @"My Text";
    return cell;
}

请尝试以下代码：

   UIActivityIndicatorView *indicator = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
indicator.frame = CGRectMake(your bounds);  
[cell addSubview:indicator];
[indicator bringSubviewToFront:self.view];
[indicator startAnimating];


        dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH,  0ul);
    dispatch_async(queue, ^{
     //This is what you will load lazily
        NSString *u=[NSString stringWithContentsOfFile:r.url encoding:NSUTF8StringEncoding error:nil];
        NSURL *imageURL=url;
        NSData *image=[NSData dataWithContentsOfURL:imageURL];
        dispatch_sync(dispatch_get_main_queue(), ^{
            CustomCell *cell = (CustomCell *)[tableView cellForRowAtIndexPath:indexPath];
            cell.imageView.image=[UIImage imageWithData:image];
            [cell setNeedsLayout];
  [indicator stopAnimating];

        });
    });
cell.cellDescription.text=r.url;// this is which you want to add in first time.

我不确定，但试试看

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

    TableCellLayout *cell = (TableCellLayout *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if(cell == nil)
    {
        cell = [[TableCellLayout alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }

    cell.cellName = [[array valueForKey:@"name"] objectAtIndex:indexPath.row];
    cell.cellImage = [UIImage imageNamed:@"placeholder.png"]; // add a placeholder    

    NSString *imageURL = [[array valueForKey:@"imageLink"] objectAtIndex:indexPath.row];
    NSURL *theURL = [NSURL URLWithString:imageURL];

    if (asynchronousImageLoader == nil){
        asynchronousImageLoader = [[AsynchronousImages alloc] init];
    }
    [asynchronousImageLoader loadImageFromURL:theURL];

    cell.cellImage = asynchronousImageLoader.image;

return cell;
}

我终于成功地通过以下方式设置了图像：

– performSelectorOnMainThread:withObject:waitUntilDone:

---

下载图像后

[cell.imageView setImageWithURL:[NSURL URLWithString:@”占位符图像：[UIImage imagename:@“placeholder.png”]]；此行显示setImageWithUrl和占位符图像的错误。请确保已将库正确添加到项目中，并且不要忘记导入“UIImageView+WebCache.h”"您希望在何处显示图像。导入图像时显示错误。文件存在何处？如果您将库正确链接到项目，则不会显示错误。阅读指南您可以告诉我如何显示活动指示器，直到图像未显示在表视图单元格中吗？我没有对表视图执行此操作，但是请尝试我更新的答案。我想在我的图库页面中实现这一点，该页面也会像上面的方法一样异步下载图像。很抱歉，这是我的错误。我已经更新了答案。请快速告诉我它是否有效？我想在这里显示指示器。dispatch\u queue\t queue=dispatch\u get\u global\u queue（DISPATCH_QUEUE_PRIORITY_HIGH，0ul）；DISPATCH_async（QUEUE，^{NSURL*imageURL=url；NSData*image=[NSData datawithcontentsofull:imageURL]；DISPATCH_sync（DISPATCH_get_main_QUEUE（），^{imageview.image=[UIImage imageWithData:data]；[scroll addSubview:imageview]；[indicator stop animating]；）; });