Question

这是我在StackOver流程中的第一篇文章，我的英语不好。我是iOS的初学者，所以我很慢一点。实际上我想从URL解析我的5个数据（包括Image）。我使用自定义tableView单元格。我的纯文本显示在自定义单元格（标签中），但图像不是。这就是我使用“dispatch_queue_t”在特定的ImageView中加载图像的原因。当我运行模拟器时，图像显示（Logo＆amp; BackGround）一个接一行完美，但问题发生在我重置模拟器时。重置后，每个单元格中加载一个图像（队列中的最后一个图像）（总共5个）。我在“viewDidLoad”中调用了我的“parsingLoad”方法，因此它只在加载viewController时加载一次。任何人都可以告诉我，我错了什么？

这是我的代码：

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

FairListCustomCell *cell = (FairListCustomCell*)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
{
    NSArray *topLabelObject = [[NSBundle mainBundle] loadNibNamed:@"FairListCustomCell" owner:self options:nil];

    for (id currentObject in topLabelObject)
    {
        if ([currentObject isKindOfClass:[UITableViewCell class]])
        {
            cell =  (FairListCustomCell*) currentObject;
            break;
        }
    }
}

cell.selectionStyle = UITableViewCellSelectionStyleNone;

currentFair = [fairs objectAtIndex:indexPath.row];

cell.fairNameLabel.text =currentFair.FairName;
cell.fairLocationLabel.text =currentFair.FairLocation;
cell.bookmarkImageView.image=[UIImage imageNamed:@"Favorite.png"];
cell.bookmarkImageView.tag=indexPath.row;

dispatch_queue_t imageQueueFairLogo = dispatch_queue_create("com.queue", NULL);
dispatch_async(imageQueueFairLogo, ^
{
    dispatch_retain(imageQueueFairLogo);
    UIImage *imageFairLogo = [UIImage imageWithData:[NSData dataWithContentsOfURL: [NSURL URLWithString:[currentFair FairLogo]]]];
    dispatch_async(dispatch_get_main_queue(), ^
    {
        cell.fairLogoImageView.image = imageFairLogo;
        #if NEEDS_DISPATCH_RETAIN_RELEASE
            dispatch_release(imageQueueFairLogo);
        #endif
    });
});

dispatch_queue_t imageQueueFairCellBackGround = dispatch_queue_create("com.queue", NULL);
dispatch_async(imageQueueFairCellBackGround, ^
{
    dispatch_retain(imageQueueFairCellBackGround);
    UIImage *imageFairCellBackGround = [UIImage imageWithData:[NSData dataWithContentsOfURL: [NSURL URLWithString:[currentFair FairCellBackGround]]]];
    dispatch_async(dispatch_get_main_queue(), ^
    {
        cell.fairCellBackGround.image = imageFairCellBackGround;
        #if NEEDS_DISPATCH_RETAIN_RELEASE
        dispatch_release(imageQueueFairCellBackGround);
        #endif
    });
});

return cell;

}

我也尝试了另外两种方式。第一： - 对两个图像使用“global_queue”（这里只是放一个样本），像这样：

imageQueueFairCellBackGround = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(imageQueueFairCellBackGround, ^
{
    dispatch_retain(imageQueueFairCellBackGround);
    UIImage *imageFairCellBackGround = [UIImage imageWithData:[NSData dataWithContentsOfURL: [NSURL URLWithString:[currentFair FairCellBackGround]]]];
    dispatch_async(dispatch_get_main_queue(), ^
    {
        cell.fairCellBackGround.image = imageFairCellBackGround;
        #if NEEDS_DISPATCH_RETAIN_RELEASE
        dispatch_release(imageQueueFairCellBackGround);
        #endif
    });
});

return cell;

第二名： - 像这样：

dispatch_queue_t fairCellBackGroundcallerQueue = dispatch_get_current_queue();
dispatch_queue_t fairCellBackGrounddownloadQueue = dispatch_queue_create("Thumb downloader", NULL);

dispatch_async(fairCellBackGrounddownloadQueue, ^
{
    UIImage *imageFairCellBackGround = [UIImage imageWithData:[NSData dataWithContentsOfURL: [NSURL URLWithString:[currentFair FairCellBackGround]]]];

    dispatch_async(fairCellBackGroundcallerQueue, ^
    {
        cell.fairCellBackGround.image = imageFairCellBackGround;
    });
});
dispatch_release(fairCellBackGrounddownloadQueue);

但仍然没有解决。如果有任何人有任何解决方案，请与我分享。非常感谢，先进。

Answer 1

我找到了这个特殊问题的解决方案。这是：

    imageQueueFairLogo = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
    dispatch_async(imageQueueFairLogo, ^
    {
        UIImage *imageFairLogo = [UIImage imageWithData:[NSData dataWithContentsOfURL: [NSURL URLWithString:[currentFair FairLogo]]]];
        dispatch_async(dispatch_get_main_queue(), ^
        {
            //[imageCache setObject:imageLogoCache forKey:currentFair.FairLogo];
            cell.fairLogoImageView.image = imageFairLogo;
            [cell setNeedsLayout];
        });
    });

当然“宣布”＆amp; “ @synthesize ”“MyClass.h”中相应的调度队列＆amp; “MyClass.m”文件是这样的：

    @property(nonatomic) dispatch_queue_t imageQueueFairLogo;
    @synthesize imageQueueFairLogo;

为“imageQueueFairCellBackGround”做同样的事情谢谢。：）

Answer 2

试试这个

if (postAndCheckInDetails.postImageURL.length != 0)
                {
                    if (!uploadImage)
                        uploadImage = (UIImageView*)[cell viewWithTag:4];

                    dispatch_queue_t checkInQueueForPostImage = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);

                    dispatch_async(checkInQueueForPostImage, ^{
                        UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:postAndCheckInDetails.postImageURL]]];

                        dispatch_sync(dispatch_get_main_queue(), ^{
                            if (image!=nil) {
                                [uploadImage setImage:image];
                                [uploadImage setFrame:CGRectMake(80, checkInDateAndTime.frame.origin.y+40, 160, 120)];
                            }

                            [cell setNeedsLayout];
                        });
                    });
                }

Answer 3

使用dispatch_retain和dispatch_release注释掉这些行，并在更新图像后添加[cell setNeedsDisplay]

使用“dispatch_queue_t”解析自定义表格单元格中的图像不能正常工作

3 个答案: