UICollectionview加载单元格时滚动波动 [英] UICollectionview Scrolling choppy when loading cells

问题描述

我的应用中有一个使用 UICollectionView 的图库。细胞大小约为70,70。我在列表中存储的库中的 ALAssetLibrary 中使用 ALAssets 。

I have a gallery in my app utilizing a UICollectionView. The cells are approximately 70,70 size. I am using ALAssets from the ALAssetLibrary in the gallery which I have stored in a list.

我使用通常的模式来填充单元格：

I am using the usual pattern for populating the cells:

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

  mycell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];
  mycell.imageView.image = [[UIImage imageWithCGImage:[alassetList objectAtIndex:indexpath.row] thumbnail]];
  return mycell;
}

我的画廊滚动起伏不定。我不明白为什么会这样。我已经尝试添加一个NSCache来缓存缩略图（想想可能创建的图像很昂贵），但这对性能没有帮助。

My gallery is scrolling choppy. I don't understand why this is. I've tried adding a NSCache to cache the thumbnail images (thinking maybe creating the images was expensive) but this did not help for the performance.

我希望用户界面与股票应用程序一样黄油。

I would expect the UI to be as buttery as the stock app.

我现在怀疑它可能是 UICollectionViewCell prepareForReuse 中的内容可能会拿着 dequeueReusableCellWithReuseIdentifier 方法但是使用我无法找到的工具。

I am now suspecting it may be something in the UICollectionViewCell prepareForReuse that may be holding up the dequeueReusableCellWithReuseIdentifier method but using instruments I was not able to find this.

还有其他任何东西可能是造成这种情况？是否有一种更快的方式来更快地准备 UICollectionViewCell 或出列？

Any other thing that may be be causing this? Is there a "faster" way to prepare the UICollectionViewCell or to dequeue them in a faster fashion?

推荐答案

所以任何有滚动问题的人都应该这个

So anybody having scrolling issues should do this

在您出列后添加这两行

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

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