I would like to be notified when the system purges any of my ODR resources so I can update UI. (Downloaded items have an overlay to indicate that they are avaialble immediately.)
There is currently no way to be notified when ODR content is cached/purged. It is left completely up to the OS, as to which content and when that content is purged. The OS takes in several factors when deciding this content, including frequency of use, age, space availablility, and many others.
Just to add that ODR was designed to be adaptive to your application, so if your app downloads new data, depending on old data will be pushed out.
I would suggest starting here with "conditionally accessing the resources", which will check if a resource is already on the device:
https://developer.apple.com/documentation/foundation/nsbundleresourcerequest/1614834-conditionallybeginaccessingresou
- Hope that helps 🙂