Optimizing CKFetchRecordZoneChangesOperation to fetch desiredKeys

In my CloudKit app, I create one zone in the private database where all the CKRecords are stored. The CKRecords can be of 10 different record types, and some of them can have CKAssets attached to them. I use

CKFetchRecordZoneChangesOperation

to find the record changes in this zone, and download them. I want to optimize the

CKFetchRecordZoneChangesOperation

so that I include only

desiredKeys

in the download, so I don't download the CKAsset at that time, but there doesn't seem to be any way to specify this per record type. Instead it seems like you can only specify

desiredKeys

on

CKFetchRecordZoneChangesOptions

, which is set on the zoneID.

So how can I specify 'desiredKeys' on my

CKFetchRecordZoneChangesOperation

fetch, considering there are different types of record types in that zone? Am I missing something simple here? The drastic option I guess is to create a different record zone for each record type, but I wouldn't want to go down that path if an alternative is possible.

Thanks for any insights.