For images, NSCache is a good way, even I think, that all these kinds of apps use a preview Image before the video start.
For large data maybe it's better to download the video and cache it on cachesDirectory using the file manager, writing the data on a file, and then, before fetching from the internet the second time, you can see if you have it on the cachesDirectory. If you'll find the file use its URL to make your logic with it.
Topic:
UI Frameworks
SubTopic:
SwiftUI
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