How to fetch all changes since latest CKServerChangeToken? – Ios swift

This is how I define fetching changes:

func fetchAllChanges(isFetchedFirstTime: Bool) {

    let zone = CKRecordZone(zoneName: "fieldservice")
    let options = CKFetchRecordZoneChangesOperation.ZoneConfiguration()
    
    options.previousServerChangeToken = Token.privateZoneServerChangeToken //initially it is nil        
    let operation = CKFetchRecordZoneChangesOperation(recordZoneIDs: [zone.zoneID], configurationsByRecordZoneID: [zone.zoneID: options])
    operation.fetchAllChanges = isFetchedFirstTime
    operation.database = CloudAssistant.shared.privateDatabase
    // another stuff
}

When I fetch all of them first time, then fetchAllChanges is false. So I only get server change token and save it for another use. No changes for records is returned. And it is ok;)

The problem is when I try to fetch it SECOND TIME. Since then nothing changed, server change token is not nil now, but fetchAllChanges is true because I need all the changes since first fetch (last server change token). It should work like this in my opinion.

But the SECOND TIME I got ALL THE CHANGES from my cloudkit (a few thousands of records and alll the changes). Why? I thought I told cloudkit that I do not want it like this. What am I doing wrong?

I have implemented @vadian answer, but my allChanges is always empty. Why?

func fetchPrivateLatestChanges(handler: ProgressHandler?) async throws -> ([CKRecord], [CKRecord.ID]) {
    /// `recordZoneChanges` can return multiple consecutive changesets before completing, so
    /// we use a loop to process multiple results if needed, indicated by the `moreComing` flag.
    var awaitingChanges = true
    
    var changedRecords = [CKRecord]()
    var deletedRecordIDs = [CKRecord.ID]()
    let zone = CKRecordZone(zoneName: "fieldservice")
    while awaitingChanges {
        /// Fetch changeset for the last known change token.
        print("🏆TOKEN: - (lastChangeToken)")
        let allChanges = try await privateDatabase.recordZoneChanges(inZoneWith: zone.zoneID, since: lastChangeToken)
        
        /// Convert changes to `CKRecord` objects and deleted IDs.
        let changes = allChanges.modificationResultsByID.compactMapValues { try? $0.get().record }
        print(changes.count)
        changes.forEach { _, record in
            print(record.recordType)
            changedRecords.append(record)
            handler?("Fetching (changedRecords.count) private records.")
        }
        
        let deletetions = allChanges.deletions.map { $0.recordID }
        deletedRecordIDs.append(contentsOf: deletetions)
        
        /// Save our new change token representing this point in time.
        lastChangeToken = allChanges.changeToken
        
        /// If there are more changes coming, we need to repeat this process with the new token.
        /// This is indicated by the returned changeset `moreComing` flag.
        awaitingChanges = allChanges.moreComing
    }
    return (changedRecords, deletedRecordIDs)
}

And here is what is repeated on console:

🏆TOKEN: – nil

0

🏆TOKEN: – Optional(<CKServerChangeToken: 0x1752a630; data=AQAAAAAAAACXf/////////+L6xlFzHtNX6UXeP5kslOE>)

0

🏆TOKEN: – Optional(<CKServerChangeToken: 0x176432f0; data=AQAAAAAAAAEtf/////////+L6xlFzHtNX6UXeP5kslOE>)

0

🏆TOKEN: – Optional(<CKServerChangeToken: 0x176dccc0; data=AQAAAAAAAAHDf/////////+L6xlFzHtNX6UXeP5kslOE>)

0

… …

This is how I use it:

TabView {
    //my tabs
}
.tabViewStyle(PageTabViewStyle())
.task {
    await loadData()
}

private func loadData() async {
    await fetchAllInitialDataIfNeeded { error in
        print("FINITO>>🏆")
        print(error)
    }
}

private func fetchAllInitialDataIfNeeded(completion: @escaping ErrorHandler) async {
    isLoading = true
    do {
        let sthToDo = try await assistant.fetchPrivateLatestChanges { info in
            self.loadingText = info
        }
        print(sthToDo)
    } catch let error as NSError {
        print(error.localizedDescription)
    }