A data token used to track client-side changes to records.
- iOS 8.0+
- macOS 10.10+
- UIKit for Mac 13.0+Beta
- tvOS 9.0+
- watchOS 3.0+
When you modify records from a fetch operation, specify a client-generated data token using this property to indicate which version of the record you last modified. Compare the data token you supplied to the data token in the next record fetch to confirm the server has successfully received the device’s last modify request.
The default value is
If you intend to change the value of this property, do so before executing the operation or submitting the operation object to a queue.