ios - 异步下载 1000 张图像并进行缓存，但会出现内存问题

Question

我有一个代码可以下载大约 1000 张图像，还可以使用 NSCache 执行缓存并在 UICollectionView 中显示图像。它可以工作，但是当 UICollectionView 滚动得非常快并且互联网速度很慢时，会收到内存警告。那么这里的问题是什么？以下是我的代码:提前致谢。

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
      ProductCollectionViewCell *cell = (ProductCollectionViewCell *)[collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];

      //set image,title of product
      cell.productLabel.text = [self.productNameArray objectAtIndex:indexPath.row];
      UIImage *image = [self.imgCache getCachedImageForKey:[self.imgUrlArray objectAtIndex:indexPath.row]];
      if (image.size.width>0) {
        [cell.productImage setImage:image];
      }
      else {
        [cell.productImage setImage:nil];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^(void){
        NSData *imgData = [NSData dataWithContentsOfURL:[NSURL URLWithString:[self.imgUrlArray objectAtIndex:indexPath.row]]];
        UIImage *img = [UIImage imageWithData:imgData];
        [cell.productImage setImage:nil];
        dispatch_async(dispatch_get_main_queue(), ^{
            if (imgData!=nil) {
                [cell.productImage setImage:img];
                [self.imgCache cacheImage:img forKey:[self.imgUrlArray objectAtIndex:indexPath.row]];
                if ([self.imgDataArray count] <= [self.productNameArray count]) {
                    [self.imgDataArray addObject:imgData];
                }
            }
        });
        if ([self.imgDataArray count] == [self.productNameArray count]){
            [self.productsView.collectionView reloadData];
        }
    });    
}
return cell;
}

Answer 1

您可以使用这个 SDWebImage

[cell.imageView sd_setImageWithURL:[NSURL URLWithString:@"http://www.domain.com/path/to/image.jpg"]
                      placeholderImage:[UIImage imageNamed:@"placeholder.png"]];