ios - 滚动时 CollectionView 滞后

Question

先生，我是初学者。我无法理解这一点。滚动 collectionView 时我遇到了延迟。我删除了 Cell-shadow 然后滞后消失了。但我想添加阴影。我的 cellforItem 代码是:

- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath
    {
        NSString *cellIdentifier = @"cellCollection";
        [self.MainCollectionView registerClass:[CVC_ImageWithLabel class] forCellWithReuseIdentifier:cellIdentifier];
        CVC_ImageWithLabel *customCell = (CVC_ImageWithLabel *)[self.MainCollectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];

        //cell text
        customCell.NameLabel.text = [data_Array objectAtIndex:indexPath.row];
        //cell image
        customCell.CellImage.image=[UIImage imageNamed:[image_Array objectAtIndex:indexPath.row]];
        customCell.CellImage.contentMode = UIViewContentModeScaleAspectFit;

        return customCell;
    }

先生，您能帮帮我吗？我曾尝试添加以下代码，但没有成功。

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

Answer 1

您应该设置图层的另一个属性 - ShadowPath:

self.layer.shadowRadius = 5;
self.layer.shadowOpacity = 0.5;
self.layer.shadowOffset = CGSizeMake(0, 1);
self.layer.shadowColor = [UIColor blackColor].CGColor;
self.layer.shadowPath = [UIBezierPath bezierPathWithRoundedRect: self.bounds cornerRadius: self.layer.shadowRadius].CGPath;

此路径定义用于构造图层阴影的轮廓，而不是使用图层的合成 Alpha channel 。使用此属性显式指定路径通常会提高渲染性能