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Optimizing UICollectionView Scrolling Performance and High-Quality Image Loading with PHCachingImageManager
Hello, I'm developing an app that displays a photo library using UICollectionView and PHCachingImageManager. I'd like to achieve a user experience similar to the native iOS Photos app, where low-quality images are shown quickly while scrolling, and higher-quality images are loaded for visible cells once scrolling stops. I'm currently using the following approach: While Scrolling: I'm using the UICollectionViewDataSourcePrefetching protocol. In the prefetchItemsAt method, I call startCachingImages with low-quality options to cache images in advance. After Scrolling Stops: In the scrollViewDidEndDecelerating method, I intend to load high-quality images for the currently visible cells. I have a few questions regarding this approach: What is the best practice for managing both low-quality and high-quality images efficiently with PHCachingImageManager? Is it correct to call startCachingImages with fastFormat options and then call it again with highQualityFormat in scrollViewDidEndDecelerating? How can I minimize the delay when a low-quality image is replaced by a high-quality one? Are there any additional strategies to help pre-load high-quality images more effectively?
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Aug ’25