iphone - uicollection View 可重用单元格图像在滚动时重新加载

Question

你好，我正在使用 UICollectionView 在我的 iPhone 应用程序中显示图像，但是当我 ScrollView 时，加载的图像消失并再次加载图像，这是因为“dequeueReusableCellWithReuseIdentifier”这是我的代码

static NSString * const kCellReuseIdentifier = @"collectionViewCell";
[self.collectionViewPack registerNib:[UINib nibWithNibName:@"CollectionViewItem" bundle:nil] forCellWithReuseIdentifier:kCellReuseIdentifier];

    - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
    {

        UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:kCellReuseIdentifier forIndexPath:indexPath];

        cell.layer.shouldRasterize = YES;
        cell.layer.rasterizationScale = [UIScreen mainScreen].scale;

        UILabel *titleLabel = (UILabel *)[cell viewWithTag:100];
        UIImageView *icon=(UIImageView *)[cell viewWithTag:101];
        //    [titleLabel setText:[NSString stringWithFormat:@"%d",indexPath.row]];
        [titleLabel setText:[NSString stringWithFormat:@"%@",[arrayImages objectAtIndex:indexPath.row]]];
        icon.image =[UIImage imageNamed:@"loading-1.png"];


        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
            NSString *imagePath = [NSString stringWithFormat:@"%@", [test.arrImages objectAtIndex:indexPath.row]];
            NSURL *imageUrl     = [NSURL URLWithString:imagePath];
            NSData *imageData   = [NSData dataWithContentsOfURL:imageUrl];
            UIImage *image      = nil;
            if (imageData){

                image = [[UIImage alloc] initWithData:imageData];
                icon.image = image;

            }

            [image release];

        });



        return cell;


    }

请帮我解决这个问题。

Answer 1

我想你需要在代码中添加一些图像缓存，我建议你使用 AFNetworking ,你可以轻松地做到:

导入“UIImageView+AFNetworking.h”

……

[cell.imageView setImageWithURL:imageUrl placeholderImage:[UIImage imageNamed:@"default"]];

而且，它有一个内部缓存，可以提供帮助:D

对于您的代码...尝试将其添加到您的代码块中

dispatch_async(dispatch_get_main_queue(), ^{
    icon.image = image;
});