On-Demand Resources
Also known as: ODR, app downloads extra content, why app keeps downloading
On-Demand Resources (ODR) let an app download content — game levels, tutorials, or extra assets — only when needed, instead of bundling everything in the initial install. iOS can purge this downloaded content automatically when storage runs low.
- Downloads app content only when it is needed
- Purgeable — iOS can delete it when space is low
- Explains changing on-device app sizes
How On-Demand Resources work
With On-Demand Resources, a developer hosts parts of an app on Apple’s servers and the app fetches them as you progress — for example, a game pulling the next chapter of levels. This keeps the App Store download small and avoids shipping content you may never reach.
Downloaded ODR content is treated as purgeable. When your device is short on space, iOS can delete it in the background, and the app re-downloads it the next time you need it — which is why an app’s on-device size can change over time.
Why an app keeps re-downloading
If a game or app seems to download data each time you open a section, ODR is often why: the resources were purged to free space and are being fetched again. Freeing storage elsewhere, or keeping the app you use most, reduces this churn.