On-Demand Resources is deprecated: moving to Background Assets

With On-Demand Resources you tag resources in Xcode and ask for them with NSBundleResourceRequest, and the system may purge them when they are no longer in use. Background Assets moves this to asset packs: each has a manifest with a download policy, essential packs arrive before first launch, prefetch packs download without blocking launch, and on-demand packs download when you ask. The system keeps downloaded packs up to date in the background and does not remove them while the app is installed, so you free space yourself.

1. Packs. Turn your ODR tags into asset packs with manifest files and pick a download policy for each. 2. Extension. Add a downloader extension from Xcode’s Background Download template, and put the app and the extension in a shared App Group. 3. Code. Replace beginAccessingResources with ensureLocalAvailability(of:) on the pack, read files with contents(at:searchingInAssetPackWithID:options:), and call remove(assetPackWithID:) when done. 4. Test. Use the local mock server that ships with Xcode. 5. Upload. Upload asset packs to App Store Connect before you distribute through TestFlight or the App Store.

Apple-Hosted Background Assets hosts up to 200GB of compressed assets with your Developer Program membership and works for apps on TestFlight or the App Store on every platform except watchOS. You can also host packs yourself with the lower-level Background Assets APIs. Apple allows the framework only for downloading additional assets, not for collecting data to identify a user or device or for advertising measurement. Show a progress indicator for foreground downloads, since even essential packs can be delayed by network drops.

iOS 27 brings several changes at once. See StoreKit 2 migration, Rosetta 2 end of support and App Store creative assets.

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