I have a model with a FamilyActivitySelection, currently i'm using a codable struct to store it with UserDefaults, but would prefer strongly to transition to Swift Data

No matter what I do, I keep getting the error Thread 1: EXC_BREAKPOINT (code=1, subcode=0x2648fc364) for the line: transactions = try modelContext.fetch(descriptor) in the code below. My app opens, but freezes on the home page and I can't click anything. I am not sure how to fix initialization issues. I am creating a financial assistant app that connects plaid and opoenai api. var descriptor = FetchDescriptor<ExpenseTransaction>() descriptor.sortBy = [SortDescriptor(\.date, order: .reverse)] descriptor.fetchLimit = 200 transactions = try modelContext.fetch(descriptor) print("Successfully loaded \(transactions.count) transactions") } catch { print("Error in loadLocalTransactions: \(error)") transactions = [] } }

I'm a first time developer for Swift, (getting on a bit!) but after programming in VB back in the late 90s I wanted to write an app for iPhone. I think I might have gone about it the wrong way, but I've got an app that works great on my iPhone or works great on my iPad. It saves the data persistently on device, but, no matter how much I try, what I read and even resorting to AI (ChatGPT & Gemini) I still can't get it to save the data on iCloud to synchronise between the two and work across the devices. I think it must be something pretty fundamental I'm doing (or more likely not doing) that is causing the issue. I'm setting up my signing and capabilities as per the available instructions but I always get a fatal error. I think it might be something to do with making fields optional, but at this point I'm second guessing myself and feeling a complete failure. Any advice or pointers would be really gratefully appreciated. I like my app and would like eventually to get it on the App Store but at this point in time I feel it should be on the failed projects heap! I've even tried a new Xcode project for iOS and asking it to use SwiftData and CloudKit - the default project should work - right? But it absolutely doesn't for me. Please send help!!

Hello, My app has had CloudKit enabled for a while, but it's not working. I get the error "Invalid bundle ID for container". Configure CloudKit in your project from TN3164 suggests changing to a new container. I tried changing to a new container, but this leads to data loss. The article recommends: "If your CloudKit container is already used in the production environment and switching to a new container leads to data loss, consider filing a feedback report with the following information to request manually associating your CloudKit container with your app ID." Where can I request this manual association? Is there anything else I can do? Thank you for your time and assistance. I’d appreciate a prompt resolution, as this issue is blocking our update. Looking forward to guidance.

Hi, Before the iOS 17.2 update the saving behavior of SwiftData was very straightforward, by default it saves to persistence storage and can be configured to save in memory only. Now it saves to memory by default and to make it save to persistence storage we need to use modelContext.Save(). But if we don't quit the App the changes will be saved after a while to persistence storage even without running modelContext.Save() ! How confusing can that be for both developer and the user ! Am I missing something here ? -- Kind Regards

I have a simple app that makes an HTTPS call to gather some JSON which I then parse and add to my SwiftData database. The app then uses a simple @Query in a view to get the data into a list. on iOS 16 this works fine. No problems. But the same code on iOS 26 (targeting iOS 18.5) crashes after about 15 seconds of idle time after the list is populated. The error message is: Could not cast value of type '__NSCFNumber' (0x1f31ee568) to 'NSString' (0x1f31ec718). and occurs when trying to access ANY property of the list. I have a stripped down version of the app that shows the crash available. To replicate the issue: open the project in Xcode 26 target any iOS 26 device or simulator compile and run the project. after the list is displayed, wait about 15 seconds and the app crashes. It is also of note that if you try to run the app again, it will crash immediately, unless you delete the app from the device. Any help on this would be appreciated. Feedback number FB20295815 includes .zip file Below is the basic code (without the data models) The Best Seller List.Swift import SwiftUI import SwiftData @main struct Best_Seller_ListApp: App { var body: some Scene { WindowGroup { ContentView() } .modelContainer (for: NYTOverviewResponse.self) } } ContentView.Swift import os.log import SwiftUI struct ContentView: View { @Environment(\.modelContext) var modelContext @State private var listEncodedName = String() var body: some View { NavigationStack () { ListsView() } .task { await getBestSellerLists() } } func getBestSellerLists() async { guard let url = URL(string: "https://api.nytimes.com/svc/books/v3/lists/overview.json?api-key=\(NYT_API_KEY)") else { Logger.errorLog.error("Invalid URL") return } do { let decoder = JSONDecoder() var decodedResponse = NYTOverviewResponse() //decode the JSON let (data, _) = try await URLSession.shared.data(from: url) decoder.keyDecodingStrategy = .convertFromSnakeCase decodedResponse = try decoder.decode(NYTOverviewResponse.self, from: data) //remove any lists that don't have list_name_encoded. Fixes a bug in the data decodedResponse.results!.lists = decodedResponse.results!.lists!.filter { $0.listNameEncoded != "" } // sort the lists decodedResponse.results!.lists!.sort { (lhs, rhs) -> Bool in lhs.displayName < rhs.displayName } //delete any potential existing data try modelContext.delete(model: NYTOverviewResponse.self) //add the new data modelContext.insert(decodedResponse) } catch { Logger.errorLog.error("\(error.localizedDescription)") } } } ListsView.Swift import os.log import SwiftData import SwiftUI @MainActor struct ListsView: View { //MARK: - Variables and Constants @Query var nytOverviewResponses: [NYTOverviewResponse] enum Updated: String { case weekly = "WEEKLY" case monthly = "MONTHLY" } //MARK: - Main View var body: some View { List { if nytOverviewResponses.isEmpty { ContentUnavailableView("No lists yet", systemImage: "list.bullet", description: Text("NYT Bestseller lists not downloaded yet")) } else { WeeklySection MonthlySection } } .navigationBarTitle("Bestseller Lists", displayMode: .large) .listStyle(.grouped) } var WeeklySection: some View { let rawLists = nytOverviewResponses.last?.results?.lists ?? [] // Build a value-typed array to avoid SwiftData faulting during sort let weekly = rawLists .filter { $0.updateFrequency == Updated.weekly.rawValue } .map { (name: $0.displayName, encoded: $0.listNameEncoded, model: $0) } .sorted { $0.name < $1.name } return Section(header: Text("Weekly lists to be published on \(nytOverviewResponses.last?.results?.publishedDate ?? "-")")) { ForEach(weekly, id: \.encoded) { item in Text(item.name).font(Font.custom("Georgia", size: 17)) } } } var MonthlySection: some View { let rawLists = nytOverviewResponses.last?.results?.lists ?? [] // Build a value-typed array to avoid SwiftData faulting during sort let monthly = rawLists .filter { $0.updateFrequency == Updated.monthly.rawValue } .map { (name: $0.displayName, encoded: $0.listNameEncoded, model: $0) } .sorted { $0.name < $1.name } return Section(header: Text("Monthly lists to be published on \(nytOverviewResponses.last?.results?.publishedDate ?? "-")")) { ForEach(monthly, id: \.encoded) { item in Text(item.name).font(Font.custom("Georgia", size: 17)) } } } }

Hi, I am currently experiencing some trouble when using parent model property in a predicate of a child model. I have an Item class that define parent-child relationship: @Model class Item { var timestamp: Date @Relationship(inverse: \Item.children) var parent: Item? var children: [Item] init(parent: Item? = nil, children: [Item] = [], timestamp: Date = .now) { self.parent = parent self.children = children self.timestamp = timestamp } } I subclass this model like that: @available(iOS 26, *) @Model final class CollectionItem: Item { /* ... */ } When i make a Query in my View like that the system crashes: @Query( filter: #Predicate<CollectionItem> { $0.parent == nil }, sort: \CollectionItem.name, ) private var collections: [CollectionItem] CrashReportError: Fatal Error in DataUtilities.swift AppName crashed due to fatalError in DataUtilities.swift at line 85. Couldn't find \CollectionItem.<computed 0x000000034005d4e8 (Optional<Item>)> on CollectionItem with fields [SwiftData.Schema.PropertyMetadata(name: "name", keypath: \CollectionItem.<computed 0x000000034003c120 (String)>, defaultValue: nil, metadata: nil), SwiftData.Schema.PropertyMetadata(name: "icon", keypath: \CollectionItem.<computed 0x000000034003ca04 (Optional<String>)>, defaultValue: nil, metadata: nil), SwiftData.Schema.PropertyMetadata(name: "timestamp", keypath: \Item.<computed 0x0000000340048018 (Date)>, defaultValue: nil, metadata: nil), SwiftData.Schema.PropertyMetadata(name: "parent", keypath: \Item.<computed 0x0000000340048a4c (Optional<Item>)>, defaultValue: nil, metadata: Optional(Relationship - name: , options: [], valueType: Any, destination: , inverseName: nil, inverseKeypath: Optional(\Item.<computed 0x0000000340048fe8 (Array<Item>)>))), SwiftData.Schema.PropertyMetadata(name: "children", keypath: \Item.<computed 0x0000000340048fe8 (Array<Item>)>, defaultValue: nil, metadata: nil)] When I query as Item it works but then i cannot sort on CollectionItem field and must add unnecessary down casting: @Query( filter: #Predicate<Item> { $0.parent == nil && $0 is CollectionItem }, ) private var items: [Item] Am I missing something? Is it a platform limitation or a known issue?

Hello, I'm planning to had an onboarding to one of my apps. I am thinking about a way for a user to not see the onboarding again if he installs the app on another device. So for example, the user completes the onboarding on its iPhone, then downloads the app on its iPad and launch it, he doesn't see the onboarding a second time. I thought about using iCloud NSUbiquitousKeyValueStored to store the onboarding completion state. But I'm not sure when the data is synced to the other device logged into the same Apple account: Immediately even if the app is not installed on the other device (independent from the app, only iCloud thing)? At the same time as the app install on the other device? After the app is first launched on the other device? Of course synchronisation will depend on the Internet connection, speed, etc. so the app should handle the case where the data is not here but what would be the best case scenario? Thank you, Axel

Hey there, Can we bundle our app with our own version of SQLite with extensions that we want. From what I've seen, we aren't allowed to add extensions to the built in IOS SQLite, so would this be the only way to use extensions. I ask this because I want to use the spell fix extension. I couldn't find a lot of people talking about adding SQLite extensions. Thank you!

I have an issue in my app, where the crashing frame is an assertionFailure in BackingData.set inside SwiftData framework. My own app doesn't appear until frame 14. I have no idea what causes this, or even how to create a reproducible project as this only happens on some devices. The frame prior to the assertionFailure is this: #1 (null) in BackingData.set(any:value:) () It seems like there is a backing data encoding happening in my Model class, and some value is causing it to fail. The model being accessed is through a relationship, and the frame in the app crashing is along the lines of Text(parent.child.name) Obviously, something is wrong in how I have made child, but the part that stand out to me is the assertionFailure in a release build

Hi all, As you know, when using SwiftData Cloudkit, all relationships are required to be optional. In my app, which is a list app, I have a model class Project that contains an array of Subproject model objects. A Subproject also contains an array of another type of model class and this chain goes on and on. In this type of pattern, it becomes really taxxing to handle the optionals the correct way, i.e. unwrap them as late as possible and display an error to the user if unable to. It seems like most developers don't even bother, they just wrap the array in a computed property that returns an empty array if nil. I'm just wondering what is the recommended way by Apple to handle these optionals. I'm not really familiar with how the CloudKit backend works, but if you have a simple list app that only saves to the users private iCloud, can I just handwave the optionals like so many do? Is it only big data apps that need to worry? Or should we always strive to handle them the correct way? If that's the case, why does it seem like most people skip over them? Be great if an Apple engineer could weigh in.

I have a SwiftData application that is using CloudKit. If user is on new device. How can I check and fetch data, instead of just waiting for it happen on its own randomly? For example, I have onboarding which I do not want user to go through again if they already have an active installation. Seems like SwiftData is severely limited in pretty much every way, specially any useful CloudKit debugging or control functionality.

I get the following fatal error when the user clicks Save in AddProductionView. Fatal error: Duplicate keys of type 'AnyHashable' were found in a Dictionary. This usually means either that the type violates Hashable's requirements, or that members of such a dictionary were mutated after insertion. As far as I’m aware, SwiftData automatically makes its models conform to Hashable, so this shouldn’t be a problem. I think it has something to do with the picker, but for the life of me I can’t see what. This error occurs about 75% of the time when Save is clicked. I'm using Xcode 16.2 and iPhone SE 2nd Gen. Any help would be greatly appreciated… Here is my code: import SwiftUI import SwiftData @main struct MyApp: App { var body: some Scene { WindowGroup { ContentView() .modelContainer(for: Character.self, isAutosaveEnabled: false) } } } @Model final class Character { var name: String var production: Production var myCharacter: Bool init(name: String, production: Production, myCharacter: Bool = false) { self.name = name self.production = production self.myCharacter = myCharacter } } @Model final class Production { var name: String init(name: String) { self.name = name } } struct ContentView: View { @State private var showingSheet = false var body: some View { Button("Add", systemImage: "plus") { showingSheet.toggle() } .sheet(isPresented: $showingSheet) { AddProductionView() } } } struct AddProductionView: View { @Environment(\.dismiss) private var dismiss @Environment(\.modelContext) var modelContext @State var production = Production(name: "") @Query var characters: [Character] @State private var characterName: String = "" @State private var selectedCharacter: Character? var filteredCharacters: [Character] { characters.filter { $0.production == production } } var body: some View { NavigationStack { Form { Section("Details") { TextField("Title", text: $production.name) } Section("Characters") { List(filteredCharacters) { character in Text(character.name) } HStack { TextField("Character", text: $characterName) Button("Add") { let newCharacter = Character(name: characterName, production: production) modelContext.insert(newCharacter) characterName = "" } .disabled(characterName.isEmpty) } if !filteredCharacters.isEmpty { Picker("Select your role", selection: $selectedCharacter) { Text("Select") .tag(nil as Character?) ForEach(filteredCharacters) { character in Text(character.name) .tag(character as Character?) } } .pickerStyle(.menu) } } } .toolbar { Button("Save") { //Fatal error: Duplicate keys of type 'AnyHashable' were found in a Dictionary. This usually means either that the type violates Hashable's requirements, or that members of such a dictionary were mutated after insertion. if let selectedCharacter = selectedCharacter { selectedCharacter.myCharacter = true } modelContext.insert(production) do { try modelContext.save() } catch { print("Failed to save context: \(error)") } dismiss() } .disabled(production.name.isEmpty || selectedCharacter == nil) } } } }

if it set com.apple.CoreData.ConcurrencyDebug 1 as launch arg the app always crashes and i cant proceed into the app. is there a way to only raise a warning for these issues so that i can go into the app and check every place in one session for coredata errors?

anyone getting the following error with CloudKit+CoreData on iOS16 RC? delete/resintall app, delete user CloudKit data and reset of environment don't fix. [error] error: CoreData+CloudKit: -[NSCloudKitMirroringDelegate _requestAbortedNotInitialized:](2044): <NSCloudKitMirroringDelegate: 0x2816f89a0> - Never successfully initialized and cannot execute request '<NSCloudKitMirroringImportRequest: 0x283abfa00> 41E6B8D6-08C7-4C73-A718-71291DFA67E4' due to error: Error Domain=NSCocoaErrorDomain Code=4864 "*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x65, 0x78, 0x61)" UserInfo={NSDebugDescription=*** -[NSKeyedUnarchiver _initForReadingFromData:error:throwLegacyExceptions:]: incomprehensible archive (0x53, 0x6f, 0x6d, 0x65, 0x20, 0x65, 0x78, 0x61)}

Hey all, This is my first app with Swift, and first app using CloudKit / iCloud - although I have launched other iOS app successfully. When I created the app, I selected "none" for storage my bundle identifier looks like this: io.mysite.appname I have the iCloud capability added, with CloudKit checked, and the container also checked that looks like this: iCloud.io.mysite.appname Push Notificaitons capability is also added, but there is no configuration. I have tried automatically managed signing, as well as a manually created provisioning profile.. Every time I build the app onto my device - when I check it out in settings, icloud is not listed. When I go through iCloud into icloud drive, the app is also not listed. I have cleaned the build many times, deleted and reinstalled the app on my phone many times. I am definitely logged into iCloud etc. Obviously I have spent plenty of times trying to debug with various LLMs, but we all seem to be at a loss for what I'm missing or doing wrong. Would love any tips or pointers I may be missing, thank you!

I am developing an app that uses CloudKit sharing. I recently upgraded my iPad to use 23A5336a. After that upgrade, I can no longer accept a share that is sent to me. I have rebooted the iPad and logged out of the iCloud account and logged back in. Every time I get a share link and tap it, it says: " The owner stopped sharing or your account (xxx) doesn't have permission to open it" This same code, running on the iOS26 device can share with device running iOS18. Is this a known defect? Anything I can do to help resolve this issue?

I'm trying to set up an application using SwiftData to have a number of models backed by a local datastore that's not synced to CloudKit, and another set of models that is. I was able to achieve this previously with Core Data using multiple NSPersistentStoreDescription instances. The set up code looks something like: do { let fullSchema = Schema([ UnsyncedModel.self, SyncedModel.self, ]) let localSchema = Schema([UnsyncedModel.self]) let localConfig = ModelConfiguration(schema: localSchema, cloudKitDatabase: .none) let remoteSchema = Schema([SyncedModel.self]) let remoteConfig = ModelConfiguration(schema: remoteSchema, cloudKitDatabase: .automatic) container = try ModelContainer(for: fullSchema, configurations: localConfig, remoteConfig) } catch { fatalError("Failed to configure SwiftData container.") } However, it doesn't seem to work as expected. If I remove the synced/remote schema and configuration then everything works fine, but the moment I add in the remote schema and configuration I get various different application crashes. Some examples below: A Core Data error occurred." UserInfo={Reason=Entity named:... not found for relationship named:..., Fatal error: Failed to identify a store that can hold instances of SwiftData._KKMDBackingData<...> Has anyone ever been able to get a similar setup to work using SwiftData?

I’m getting a 0xdead10cc crash in a basic CoreData/CloudKit application. I only have one CoreData save call and its made when the app is in the foreground and it's minor so I don't think its being caused by that. My best guess is that it's related to background syncing of CloudKit. Does anyone know how to fix it? I've been advised that adding the following code around any saves will fix it, but it seems weird that this is the solution. I would expect the inner CoreData/CloudKit engine to handle this. ProcessInfo().performActivity(reason: "Persisting to context") { // Save to context here } Here is the crashing thread Thread 7: 0 libsystem_kernel.dylib 0x00000001edc086f4 guarded_pwrite_np + 8 (:-1) 1 libsqlite3.dylib 0x00000001ca71b6e4 seekAndWrite + 456 (sqlite3.c:44287) 2 libsqlite3.dylib 0x00000001ca6d5df4 unixWrite + 180 (sqlite3.c:44365) 3 libsqlite3.dylib 0x00000001ca723b90 pagerWalFrames + 872 (sqlite3.c:67093) 4 libsqlite3.dylib 0x00000001ca6d5b14 sqlite3PagerCommitPhaseOne + 316 (sqlite3.c:70409) 5 libsqlite3.dylib 0x00000001ca6c6494 sqlite3BtreeCommitPhaseOne + 172 (sqlite3.c:81106) 6 libsqlite3.dylib 0x00000001ca6c605c vdbeCommit + 1136 (sqlite3.c:94124) 7 libsqlite3.dylib 0x00000001ca69f778 sqlite3VdbeHalt + 1340 (sqlite3.c:94534) 8 libsqlite3.dylib 0x00000001ca6c0618 sqlite3VdbeExec + 42648 (sqlite3.c:103922) 9 libsqlite3.dylib 0x00000001ca6b56c0 sqlite3_step + 960 (sqlite3.c:97886) 10 CoreData 0x00000001a459ab38 _execute + 128 (NSSQLiteConnection.m:4614) 11 CoreData 0x00000001a45fe004 -[NSSQLiteConnection commitTransaction] + 728 (NSSQLiteConnection.m:3278) 12 CoreData 0x00000001a469888c _executeGenerateObjectIDRequest + 388 (NSSQLCore_Functions.m:6021) 13 CoreData 0x00000001a46986a4 -[NSSQLGenerateObjectIDRequestContext executeRequestCore:] + 28 (NSSQLObjectIDRequestContext.m:42) 14 CoreData 0x00000001a45fb380 -[NSSQLStoreRequestContext executeRequestUsingConnection:] + 240 (NSSQLStoreRequestContext.m:183) 15 CoreData 0x00000001a45fb0a8 __52-[NSSQLDefaultConnectionManager handleStoreRequest:]_block_invoke + 60 (NSSQLConnectionManager.m:307) 16 CoreData 0x00000001a45fafe0 __37-[NSSQLiteConnection performAndWait:]_block_invoke + 48 (NSSQLiteConnection.m:755) 17 libdispatch.dylib 0x00000001a4357fa8 _dispatch_client_callout + 20 (object.m:576) 18 libdispatch.dylib 0x00000001a43677fc _dispatch_lane_barrier_sync_invoke_and_complete + 56 (queue.c:1104) 19 CoreData 0x00000001a45b5ba4 -[NSSQLiteConnection performAndWait:] + 176 (NSSQLiteConnection.m:752) 20 CoreData 0x00000001a45b5a68 -[NSSQLDefaultConnectionManager handleStoreRequest:] + 248 (NSSQLConnectionManager.m:302) 21 CoreData 0x00000001a45b5938 -[NSSQLCoreDispatchManager routeStoreRequest:] + 228 (NSSQLCoreDispatchManager.m:60) 22 CoreData 0x00000001a45b573c -[NSSQLCore dispatchRequest:withRetries:] + 172 (NSSQLCore.m:4044) 23 CoreData 0x00000001a46737b4 -[NSSQLCore _obtainPermanentIDsForObjects:withNotification:error:] + 1324 (NSSQLCore.m:2830) 24 CoreData 0x00000001a460ba98 -[NSSQLCore _prepareForExecuteRequest:withContext:error:] + 272 (NSSQLCore.m:2946) 25 CoreData 0x00000001a460a0f8 __65-[NSPersistentStoreCoordinator executeRequest:withContext:error:]_block_invoke.547 + 8988 (NSPersistentStoreCoordinator.m:2995) 26 CoreData 0x00000001a45d6660 -[NSPersistentStoreCoordinator _routeHeavyweightBlock:] + 264 (NSPersistentStoreCoordinator.m:668) 27 CoreData 0x00000001a45ded28 -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 1200 (NSPersistentStoreCoordinator.m:2810) 28 CoreData 0x00000001a4655988 -[NSManagedObjectContext save:] + 984 (NSManagedObjectContext.m:1593) 29 CoreData 0x00000001a46f47dc __52+[NSCKEvent beginEventForRequest:withMonitor:error:]_block_invoke_2 + 352 (NSCKEvent.m:76) 30 CoreData 0x00000001a45c28f0 developerSubmittedBlockToNSManagedObjectContextPerform + 476 (NSManagedObjectContext.m:3984) 31 libdispatch.dylib 0x00000001a4357fa8 _dispatch_client_callout + 20 (object.m:576) 32 libdispatch.dylib 0x00000001a43677fc _dispatch_lane_barrier_sync_invoke_and_complete + 56 (queue.c:1104) 33 CoreData 0x00000001a4615c34 -[NSManagedObjectContext performBlockAndWait:] + 308 (NSManagedObjectContext.m:4108) 34 CoreData 0x00000001a46f45ac __52+[NSCKEvent beginEventForRequest:withMonitor:error:]_block_invoke + 192 (NSCKEvent.m:66) 35 CoreData 0x00000001a4825e68 -[PFCloudKitStoreMonitor performBlock:] + 92 (PFCloudKitStoreMonitor.m:148) 36 CoreData 0x00000001a46f4394 +[NSCKEvent beginEventForRequest:withMonitor:error:] + 256 (NSCKEvent.m:61) 37 CoreData 0x00000001a47cc6ec __57-[NSCloudKitMirroringDelegate _performExportWithRequest:]_block_invoke + 260 (NSCloudKitMirroringDelegate.m:1433) 38 CoreData 0x00000001a47c9970 __92-[NSCloudKitMirroringDelegate _openTransactionWithLabel:assertionLabel:andExecuteWorkBlock:]_block_invoke + 72 (NSCloudKitMirroringDelegate.m:957) 39 libdispatch.dylib 0x00000001a4356248 _dispatch_call_block_and_release + 32 (init.c:1549) 40 libdispatch.dylib 0x00000001a4357fa8 _dispatch_client_callout + 20 (object.m:576) 41 libdispatch.dylib 0x00000001a435f5cc _dispatch_lane_serial_drain + 768 (queue.c:3934) 42 libdispatch.dylib 0x00000001a4360158 _dispatch_lane_invoke + 432 (queue.c:4025) 43 libdispatch.dylib 0x00000001a436b38c _dispatch_root_queue_drain_deferred_wlh + 288 (queue.c:7193) 44 libdispatch.dylib 0x00000001a436abd8 _dispatch_workloop_worker_thread + 540 (queue.c:6787) 45 libsystem_pthread.dylib 0x0000000227213680 _pthread_wqthread + 288 (pthread.c:2696) 46 libsystem_pthread.dylib 0x0000000227211474 start_wqthread + 8 (:-1)

I have transitioned to CKSyncEngine for syncing data to iCloud, and it is working quite well. I have a question regarding best practices for modifying and saving a CKRecord which already exists in the private or shared database. In my current app, most CKRecords will never be modified after saving to the database, so I do not persist a received record locally after updating my local data model. In the rare event that the local data for that record is modified, I manually fetch the associated server record from the database, modify it, and then use CKSyncEngine to save the modified record. As an alternative method, I can create a new CKRecord locally with the corresponding recordID and the modified data, and then use CKSyncEngine to attempt to save that record to the database. Doing so generates an error in the delegate method handleSentRecordZoneChanges, where I receive the local record I tried to save back inevent.failedRecordSaves with a .serverRecordChanged error, along with the corresponding server CKRecord. I can then update that server record with the local data and re-save using CKSyncEngine. I have not yet seen any issues when doing it this way. The advantage of the latter method is that CKSyncEngine handles the entire database operation, eliminating the manual fetch step. My question is: is this an acceptable practice, or could this result in other unforeseen issues?