The maximum length of time that may have elapsed since the store previously fetched data before fulfilling a fault issues a new fetch.
- iOS 3.0+
- macOS 10.4+
- Mac Catalyst 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
- Core Data
The staleness interval controls whether fulfilling a fault uses data previously fetched by the application, or issues a new fetch (see also
refresh). The staleness interval does not affect objects currently in use (that is, it is not used to automatically update property values from a persistent store after a certain period of time).
The expiration value is applied on a per object basis. It is the relative time until cached data (snapshots) should be considered stale. For example, a value of 300.0 informs the context to utilize cached information for no more than 5 minutes after an object was originally fetched.
Note that the staleness interval is a hint and may not be supported by all persistent store types. It is not used by XML and binary stores, because these stores maintain all current values in memory.
The default is a negative value, which represents infinite staleness allowed.
0 represents “no staleness acceptable”.