Apple added a subtle solution for developers in iOS 5.0.1 that addresses the issue of purged app data. In iOS 5.0, apps were suddenly restricted from caching large amounts of data in-app for offline access. Apps were effectively “cleaned” of temporary data when iOS 5 determined that the app was taking up too much space.
Previously, iOS would allow an app to store needed information, such as saved web articles for a news app, in a temporary cache that wouldn’t slow down iTunes backups, restores, and syncs. When Apple introduced iCloud, the company became more aggressive about not allowing apps to temporarily store too much information in-app.
In the recently released iOS 5.0.1 beta 1 and beta 2, Apple has provided developers with a new way to “specify files that should remain on device, even in low storage situations.”