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.我正在使用存储在列表中的库中 ALAssetLibrary
中的 ALAssets
.
我正在使用通常的模式来填充单元格:
-(UICollectionViewCell*)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{mycell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];mycell.imageView.image = [[UIImage imageWithCGImage:[alassetList objectAtIndex:indexpath.row] thumbnail]];返回菌丝;}
我的画廊滚动不连贯.我不明白为什么会这样.我尝试添加一个 NSCache 来缓存缩略图图像(认为创建图像可能很昂贵)但这对性能没有帮助.
我希望 UI 与股票应用程序一样流畅.
我现在怀疑它可能是 UICollectionViewCell prepareForReuse
中的某些东西,它可能阻止了 dequeueReusableCellWithReuseIdentifier
方法,但使用我无法找到的工具.p>
还有其他可能导致此问题的原因吗?有没有一种更快"的方法来准备 UICollectionViewCell
或以更快的方式 dequeue
它们?
所以任何有滚动问题的人都应该这样做这个
在你的出队后添加这两行
cell.layer.shouldRasterize = YES;cell.layer.rasterizationScale = [UIScreen mainScreen].scale;
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.
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;
}
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.
I would expect the UI to be as buttery as the stock app.
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.
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?
So anybody having scrolling issues should do this
add these 2 lines after your dequeue
cell.layer.shouldRasterize = YES;
cell.layer.rasterizationScale = [UIScreen mainScreen].scale;
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