CollectionView 图像在滚动时闪烁 [英] CollectionView images are flashing while scrolling

问题描述

我在我的 collectionView 中使用以下代码:cellForItemAtIndexPath:

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *identifier = @"Cell";
    
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
    
    UIImageView *recipeImageView = (UIImageView *)[cell viewWithTag:100];
    recipeImageView.image = nil;
    if ([ImageArray count] >0){
        
            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^(void) {
                NSData *data0 = [NSData dataWithContentsOfURL: [NSURL URLWithString:[ImageArray objectAtIndex:indexPath.row]]];
                UIImage *image = [UIImage imageWithData: data0];
                
                dispatch_sync(dispatch_get_main_queue(), ^(void) {
                    recipeImageView.image = image;
                });
            });
        
    }
    
    [spinnerShow stopAnimating];
    
    cell.layer.shouldRasterize = YES;
    cell.layer.rasterizationScale = [UIScreen mainScreen].scale;
    
    return cell;
}

问题是，如果我滚动集合视图，图像会闪烁.为什么呢?滚动时如何防止图像闪烁?

The problem is that, the images are flashing if I scroll the collection view. Why is that so? How can I be able to prevent images from flashing when Im scrolling it?

推荐答案

我认为根本原因是加载下面 2 行图像的成本:

I think the root reason is the cost for loading image of 2 line below :

NSData *data0 = [NSData dataWithContentsOfURL: [NSURL URLWithString:[ImageArray objectAtIndex:indexPath.row]]];
UIImage *image = [UIImage imageWithData: data0];

我的解决方案是使用 AFNetworking 加载图片过程，请参考链接:https://github.com/AFNetworking/AFNetworking

My solution is use AFNetworking for loading image process, please reference to link : https://github.com/AFNetworking/AFNetworking

安装 AFNetworking 后，您只需:

After install AFNetworking, you simply :

if ([ImageArray count] >0){
    [recipeImageView setImageWithURL:[NSURL URLWithString:[ImageArray objectAtIndex:indexPath.row]] placeholderImage:nil];
}

希望你喜欢这个！

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