CloudKit Public Records And Changes not Downloaded - ios

Question

CloudKit Public Records And Changes not Downloaded
I have a CloudKit app with records for both a Public and a Custom Private
Zone. I seem to have the change token process working for the custom
private zone but am unable to get the public data to work. The code I am
using is identical for both databases except for the public/private
names and using the default zone for the public. I understand that
subscriptions do not work on default zones, but I could not find any
references to limitations on change tokens for public data. Xcode 10.1, iOS 12.0
I create my PubicData class and initialize it:
var publicDatabase : CKDatabase!
init() {
let kAppDelegate = UIApplication.shared.delegate as! AppDelegate
context = kAppDelegate.context
let container = CKContainer.default()
publicDatabase = container.publicCloudDatabase
}//init
the download function that is called from the app entry scene - a tableview:
func downloadPublicUpdates(finishClosure : # escaping(UIBackgroundFetchResult) -> Void) {
var listRecordsUpdated : [CKRecord] = []
var listRecordsDeleted : [String : String] = [:]
var publicChangeToken : CKServerChangeToken!
var publicChangeZoneToken : CKServerChangeToken!
let userSettings = UserDefaults.standard
if let data = userSettings.value(forKey: "publicChangeToken") as? Data {
if let token = try? NSKeyedUnarchiver.unarchivedObject(ofClass : CKServerChangeToken.self, from : data) {
publicChangeToken = token
print("publicChangeToken exists")
}
} else {
print("userSettings entry for publicChangeToken does not exist")
}//if let data
if let data = userSettings.value(forKey: "publicChangeZoneToken") as? Data {
if let token = try? NSKeyedUnarchiver.unarchivedObject(ofClass: CKServerChangeToken.self, from: data) {
publicChangeZoneToken = token
}
}//if let data
let zone = CKRecordZone.default()
var zonesIDs : [CKRecordZone.ID] = [zone.zoneID]
let operation = CKFetchDatabaseChangesOperation(previousServerChangeToken: publicChangeToken)
operation.recordZoneWithIDChangedBlock = {(zoneID) in
zonesIDs.append(zoneID)
}
operation.changeTokenUpdatedBlock = {(token) in
publicChangeToken = token
}
operation.fetchDatabaseChangesCompletionBlock = {(token, more, error) in
if error != nil{
finishClosure(UIBackgroundFetchResult.failed)
} else if !zonesIDs.isEmpty {
publicChangeToken = token
let configuration = CKFetchRecordZoneChangesOperation.ZoneConfiguration()
configuration.previousServerChangeToken = publicChangeZoneToken
let fetchOperation = CKFetchRecordZoneChangesOperation(recordZoneIDs: zonesIDs, configurationsByRecordZoneID: [zonesIDs[0] : configuration])
fetchOperation.recordChangedBlock = {(record) in
listRecordsUpdated.append(record)
}//fetchOperation.recordChangedBlock
fetchOperation.recordWithIDWasDeletedBlock = {(recordID, recordType) in
listRecordsDeleted[recordID.recordName] = recordType
}//fetchOperation.recordWithIDWasDeletedBlock
fetchOperation.recordZoneChangeTokensUpdatedBlock = {(zoneID, token, data) in
publicChangeZoneToken = token
}//fetchOperation.recordZoneChangeTokensUpdatedBlock
fetchOperation.recordZoneFetchCompletionBlock = {(zoneID, token, data, more, error) in
if let ckerror = error as? CKError {
self.processErrors(error: ckerror)
} else {
publicChangeZoneToken = token
self.updateLocalRecords(listRecordsUpdated : listRecordsUpdated)
self.deleteLocalRecords(listRecordsDeleted : listRecordsDeleted)
listRecordsUpdated.removeAll()
listRecordsDeleted.removeAll()
}//if else
}//fetchOperation.recordZoneFetchCompletionBlock
fetchOperation.fetchRecordZoneChangesCompletionBlock = {(error) in
if error != nil {
print("Error fetchRecordZoneChangesCompletionBlock")
finishClosure(UIBackgroundFetchResult.failed)
} else {
if publicChangeToken != nil {
if let data = try? NSKeyedArchiver.archivedData(withRootObject: publicChangeToken, requiringSecureCoding: false) {
userSettings.set(data, forKey : "publicChangeToken")
}
}//if changeToken != nil
if publicChangeZoneToken != nil {
if let data = try? NSKeyedArchiver.archivedData(withRootObject: publicChangeZoneToken, requiringSecureCoding: false) {
userSettings.set(data, forKey : "publicChangeZoneToken")
}
}
//self.updateInterface()
self.updateLocalReferences()
finishClosure(UIBackgroundFetchResult.newData)
}
}//fetchOperation.fetchRecordZoneChangesCompletionBlock
self.publicDatabase.add(fetchOperation)
} else {//else if !zonesIDs.isEmpty
finishClosure(UIBackgroundFetchResult.noData)
}//if zoneid not empty
}//fetchDatabaseChangesCompletionBlock
print("listRecordsUpdated.count is \(listRecordsUpdated.count)")
publicDatabase.add(operation)
}//downloadPublicUpdates
Outside of class: var PD = PDData()
I call the download method in viewDidLoad from the initial TableViewController:
PD.downloadPublicUpdates { (result) in
print("in ctvc viewDidLoad and downloadPublicUpdates")
switch result {
case .noData:
print("no data")
case .newData:
print("new data")
case .failed:
print("failed to get data")
}//switch
}//downloadPublicUpdates
The console output is always:
userSettings entry for publicChangeToken does not exist
listRecordsUpdated.count is 0
in ctvc viewDidLoad and downloadPublicUpdates
failed to get data
Any guidance would be appreciated.

Answer 1

There are no change tokens available in a public database. Those only exist in private and shared databases.
To keep things in sync, you typically have to keep a modification date on records locally, and then query for stuff that is newer on the CloudKit server using a CKQueryOperation.
Good luck!