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ModelContext.model(for:) returns deleted objects
I'm writing some tests to confirm the behavior of my app. White creating a model actor to delete objects I realized that ModelContext.model(for:) does return objects that are deleted. I was able to reproduces this with this minimal test case: @Model class Activity { init() {} } struct MyLibraryTests { let modelContainer = try! ModelContainer( for: Activity.self, configurations: ModelConfiguration( isStoredInMemoryOnly: true ) ) init() throws { let context = ModelContext(modelContainer) context.insert(Activity()) try context.save() } @Test func modelForIdAfterDelete() async throws { let context = ModelContext(modelContainer) let id = try context.fetch(FetchDescriptor<Activity>()).first!.id context.delete(context.model(for: id) as! Activity) try context.save() let result = context.model(for: id) as? Activity #expect(result == nil) // Expectation failed: (result → MyLibrary.Activity) == nil } @Test func fetchDescriptorAfterDelete() async throws { let context = ModelContext(modelContainer) let id = try context.fetch(FetchDescriptor<Activity>()).first!.id context.delete(context.model(for: id) as! Activity) try context.save() let result = try context.fetch( FetchDescriptor<Activity>(predicate: #Predicate { $0.id == id }) ).first #expect(result == nil) } } Here I create a new context, insert an model and save it. The test modelForIdAfterDelete does fail, as result still contains the deleted object. I also tried to check #expect(result!.isDeleted), but it is also false. With the second test I use a FetchDescriptor to retrieve the object by ID and it correctly returns nil. Shouldn't both methods use a consistent behavior?
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132
May ’25
CKShare(rootRecord:) Returns Share with Nil Root Even When All CloudKit Best Practices Followed (iOS 26.2.1)
I’m seeing an issue with CloudKit sharing in iOS 26.2.1: When I call CKShare(rootRecord:) with a brand-new record in a fresh custom zone, the share is created with no root attached (rootFromShare == nil). After saving both the root and share in a single CKModifyRecordsOperation, fetching the share from the server still shows no root reference (rootRecordID == nil). No errors are thrown, but sharing simply fails. Key facts: • Custom zone created and confirmed (sharing enabled, capsRaw=7/15) • Brand-new record type and fresh IDs each run • Never reusing records or shares • Saving both root and share together in one operation • No default zone usage; always custom private zone Tested: • Multiple devices, iCloud accounts, and app versions • Both simulator and physical device Debug logs consistently show: • SHARE_CREATE_SHARE_LOCAL ... rootFromShare=nil • After save/fetch: rootRecordID=nil on server Has anyone seen this? Is there a new CloudKit regression in iOS 26.x, or am I missing something subtle? Minimal sample project and full debug logs available if needed. Any insights or workarounds would be hugely appreciated!
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182
3w
Deleting Production Database SwiftData
Hi all, I have setup my app to use SwiftData with CloudKit sync. I have a production environment and development environment. I can reset the development environment for myself and all users in CloudKit console, but I can't reset the production one as it's tried to users' iCloud accounts, so I've added a button in-app for that feature. In the onboarding of my app, I pre-seed the DB with some default objects, which should be persisted between app install. The issue I'm running into is that I'm unable to force-pull these models from iCloud during the onboarding of a clean re-install, which leads to the models later appearing as duplicates once the user has been on the app for a few minutes and it has pulled from their iCloud account. If anyone has any suggestions on how to handle this issue, I would greatly appreciate it.
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259
Jan ’26
SwiftData Unidirectional Relationships
Hi everyone I would like to achieve having unidirectional relationships in my SwiftData project (which I believe is possible: https://developer.apple.com/documentation/updates/swiftdata?changes=_9) but I'm afraid I'm struggling to overcome the errors I'm experiencing. For example, I have the following models: @Model final class Quota { @Attribute(.unique) var id: UUID var allowance: Int @Relationship(inverse: nil) var fish: Fish init(id: UUID = UUID(), fish: Fish, allowance: Int) { self.id = id self.fish = fish self.allowance = allowance } } @Model final class Fish { @Attribute(.unique) var id: Int var name: String init(id: Int, name: String) { self.id = id, self.name = name } } However, when I attempt to save a quota as so: let quota: Quota = .init(fish: Fish(id: 2, name: "Salmon"), allowance: 50) modelContext?.insert(quota) try save() I keep getting the following error: SwiftData.DefaultStore save failed with error: Error Domain=NSCocoaErrorDomain Code=1570 "%{PROPERTY}@ is a required value." UserInfo={NSValidationErrorObject=<NSManagedObject: 0x600002217390> (entity: Fish; id: 0x83319d001151328d <x-coredata://C76A2A64-146E-432F-A565-319B5A2F23F5/Fish/p12>; data: { id = nil; }), NSLocalizedDescription=%{PROPERTY}@ is a required value., NSValidationErrorKey=id, NSValidationErrorValue=null} %{PROPERTY}@ is a required value. However, if I set up Quota and Fish with an inverse relationship then the data saves as expected, so I'm a little confused. Is there anyone out there who can provide some guidance as to why I'm seeing this error when I try to save a record in SwiftData with no inverse relationship? I do fully understand about unidirectional vs bidirectional relationships but I have a scenario where I need the relationship to be unidirectional. Also, as a side note, the Fish record already exists in my database, but if I delete it and try to save the record I still see this error. Thank you so much in advance for any help.
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3d
Debugging/Fixing deleted relationship objects with SwiftData
Using SwiftData and this is the simplest example I could boil down: @Model final class Item { var timestamp: Date var tag: Tag? init(timestamp: Date) { self.timestamp = timestamp } } @Model final class Tag { var timestamp: Date init(timestamp: Date) { self.timestamp = timestamp } } Notice Tag has no reference to Item. So if I create a bunch of items and set their Tag. Later on I add the ability to delete a Tag. Since I haven't added inverse relationship Item now references a tag that no longer exists so so I get these types of errors: SwiftData/BackingData.swift:875: Fatal error: This model instance was invalidated because its backing data could no longer be found the store. PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(url: x-coredata://EEC1D410-F87E-4F1F-B82D-8F2153A0B23C/Tag/p1), implementation: SwiftData.PersistentIdentifierImplementation) I think I understand now that I just need to add the item reference to Tag and SwiftData will nullify all Item references to that tag when a Tag is deleted. But, the damage is already done. How can I iterate through all Items that referenced a deleted tag and set them to nil or to a placeholder Tag? Or how can I catch that error and fix it when it comes up? The crash doesn't occur when loading an Item, only when accessing item.tag?.timestamp, in fact, item.tag?.id is still ok and doesn't crash since it doesn't have to load the backing data. I've tried things like just looping through all items and setting tag to nil, but saving the model context fails because somewhere in there it still tries to validate the old value. Thanks!
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380
Mar ’25
Feedback/issues for SwiftData custom store
Hello, thank you Apple for supporting custom store with SwiftData and the Schema type is superb to work with. I have successfully set one up with SQL and have some feedback and issues regarding its APIs. There’s a highlighted message in the documentation about not using internal restricted symbols directly, but they contradict with the given protocols and I am concerned about breaking any App Store rules. Are we allowed to use these? If not, they should be opened up as they’re useful. BackingData is required to set up custom snapshots, initialization, and getting/setting values. And I want to use it with createBackingData() to directly initialize instances from snapshots when transferring them between server and client or concurrency. RelationshipCollection for casting to-many relationships from backing data or checking if an array contains a PersistentModel. SchemaProperty for type erasure in a collection. Schema.Relationship has KeyPath properties, but it is missing for Schema.Attribute and Schema.CompositeAttribute. Which means you can’t purely depend on the schema to map data. I am unable to access the properties of a custom struct type in a predicate unless I use Mirror with schemaMetadata() or CustomStringConvertible on the KeyPath directly to extract it. Trivial, but… the KeyPath property name is inconsistent (it’s all lowercase). It would be nice to retrieve property names from custom struct types, since you are unable access CodingKeys that are auto synthesized by Codable for structs. But I recently realized they’re a part Schema.CompositeAttribute, however I don’t know how to match these without the KeyPath… I currently map my entities using CodingKeys to their PredicateCodableKeyPathProviding.… but I wish for a simpler alternative! It’s unclear how to provide the schema to the snapshot before new models are created. I currently use a static property, but I want to make it flexible if more schemas and configurations are added later on. I considered saving and loading the schema in a temporary location, but doubtful that the KeyPath values will be available as they are not Codable. I suspect schemaMetadata() has the information I need to map the backing data without a schema for snapshots, but as mentioned previously, properties are inaccessible… Allow access to entity metatypes, like value types from SchemaProperty. They’re useful for getting data out of snapshots and casting them to CodingKeys and PredicateCodableKeyPathProviding. They do not carry over when you provide them in the Schema. I am unable to retrieve the primary key from PersistentIdentifier. It seems like once you create one, you can’t get it out, like the DataStoreConfiguration in ModelContainer is not the one you used to set it up. I cannot cast it, it is an entirely different struct? I have to use JSONSerialization to extract it, but I want to get it directly since it is not a column in my database. It is transformed when it goes to/from my tables. It’s unknown how to support some schema options, such as Spotlight and CloudKit. Allow for extending macro options, such as adding options to set as primary key, whether to auto increment, etc… You can create a schema for super and sub entities, but it doesn’t appear you can actually set them up from the @Model macro or use inheritance on these models… SwiftData history tracking seems incomplete for HistoryDelete, because that protocol requires HistoryTombstone, but this type cannot be instantiated, nor does it contain anything useful to infer from. As an aside, I want to create my own custom ModelActor that is a global actor. However, I’m unable to replicate the executor that Apple provides where the executor has a ModelContext, because this type does not conform to Sendable. So how did Apple do this? The documentation doesn’t mention unchecked Sendable, but I figure if the protocol is available then we would be able to set up our own. And please add concurrency features! Anyway, I hope for more continued support in the future and I am looking forward to what’s new this WWDC! 😊
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157
May ’25
iCloud Mail being rejected by Barracuda Email Protection due to missing PTR record.
My client is using iCloud Mail with his custom domain and he communicated with many govt organizations which seem to all be using Barracuda Email Protection for their spam prevention. I have properly configured his SPF, DKIM & DMARC DNS records however his emails were still being rejected. (Email header below) I contacted Barracuda support with the email header and they replied saying that the emails were rejected becuase Apple Mail has missing PTR records. I have sent dozens of emails for testing and looking at all their headers I can see (ms-asmtp-me-k8s.p00.prod.me.com [17.57.154.37]) which does not have a PTR record. ----FULL EMAIL HEADER WITH 3RD PARTY DOMAINS REMOVED----- <recipient_email_address>: host d329469a.ess.barracudanetworks.com[209.222.82.255] said: 550 permanent failure for one or more recipients (recipient_email_address:blocked) (in reply to end of DATA command) Reporting-MTA: dns; p00-icloudmta-asmtp-us-west-3a-100-percent-10.p00-icloudmta-asmtp-vip.icloud-mail-production.svc.kube.us-west-3a.k8s.cloud.apple.com X-Postfix-Queue-ID: 8979C18013F8 X-Postfix-Sender: rfc822; sender_email_address Arrival-Date: Thu, 20 Mar 2025 12:30:05 +0000 (UTC) Final-Recipient: rfc822; @****** Original-Recipient: rfc822;recipient_email_address Action: failed Status: 5.0.0 Remote-MTA: dns; d329469a.ess.barracudanetworks.com Diagnostic-Code: smtp; 550 permanent failure for one or more recipients (recipient_email_address:blocked) Return-Path: <sender_email_address> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sender_domain; s=sig1; bh=CyUt/U7mIHwXB5OQctPjRH/OxLH7GsLR54JjGuRkj9Y=; h=From:Message-Id:Content-Type:Mime-Version:Subject:Date:To:x-icloud-hme; b=hwEbggsctiCRlMlEgovBTjB/0sPRCb2k+1wzHRZ2dZNrZdOqvFSNWU+Aki9Bl8nfv eEOoXz5qWxO2b2rEBl08lmRQ3hCyroayIn4keBRrgkxL1uu4zMTaDUHyau2vVnzC3h ZmwQtQxiu7QvTS/Sp8jjJ/niOPSzlfhphqMxnQAZi/jmJGcZPadT8K+7+PhRllVnI+ TElJarN1ORQu+CaPGhEs9/F7AIcjJNemnVg1cude7EUuO9va8ou49oFExWTLt7YSMl s+88hxxGu3GugD3eBnitzVo7s7/O9qkIbDUjk3w04/p/VOJ+35Mvi+v/zB9brpYwC1 B4dZP+AhwJDYA== Received: from smtpclient.apple (ms-asmtp-me-k8s.p00.prod.me.com [17.57.154.37]) by p00-icloudmta-asmtp-us-west-3a-100-percent-10.p00-icloudmta-asmtp-vip.icloud-mail-production.svc.kube.us-west-3a.k8s.cloud.apple.com (Postfix) with ESMTPSA id 8979C18013F8; Thu, 20 Mar 2025 12:30:05 +0000 (UTC) From: Marcel Brunel <sender_email_address> Message-Id: <2E8D69EA-FCA6-4F5D-9D42-22A955C073F6@sender_domain> Content-Type: multipart/alternative; boundary="Apple-Mail=_F9AC7D29-8520-4B25-9362-950CB20ADEC5" Mime-Version: 1.0 (Mac OS X Mail 16.0 (3826.400.131.1.6)) Subject: Re: [EXTERNAL] - Re: Brunel - 2024 taxes Date: Thu, 20 Mar 2025 07:29:27 -0500 In-Reply-To: <SA0PR18MB350300DE7274C018F66EEA24F2D82@SA0PR18MB3503_namprd18_prod_outlook_com> To: Troy Womack <recipient_email_address> References: <SA0PR18MB350314D0B88E283C5C8E1BB6F2DE2@SA0PR18MB3503_namprd18_prod_outlook_com> <9B337A3E-D373-48C5-816F-C1884BDA6F42@sender_domain> <SA0PR18MB350341A7172E8632D018A910F2D82@SA0PR18MB3503_namprd18_prod_outlook_com> <SA0PR18MB350300DE7274C018F66EEA24F2D82@SA0PR18MB3503_namprd18_prod_outlook_com> X-Mailer: Apple Mail (2.3826.400.131.1.6) X-Proofpoint-ORIG-GUID: uqebp2OIbPqBr3dYsAxdFVkCNbM5Cxyl X-Proofpoint-GUID: uqebp2OIbPqBr3dYsAxdFVkCNbM5Cxyl X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1093,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-03-20_03,2025-03-19_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 clxscore=1030 suspectscore=0 mlxlogscore=999 mlxscore=0 phishscore=0 malwarescore=0 spamscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2411120000 definitions=main-2503200077
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201
Mar ’25
Default zone is not accessible in shared DB - cloudKit
I am trying to save to cloud kit shared database. The shared database does not allow zones to be set up. How do I save to sharedCloudDatabase without a zone? private func addItem(recordType: String, name: String) { let record = CKRecord(recordType: recordType) record[Constances.field.name] = name as CKRecordValue record[Constances.field.done] = false as CKRecordValue record[Constances.field.priority] = 0 as CKRecordValue CKContainer.default().sharedCloudDatabase.save(record) { [weak self] returnRecord, error in if let error = error { print("Error saving record: \(record[Constances.field.name] as? String ?? "No Name"): \n \(error)") return } } } The following error message prints out: Error saving record: Milk: &lt;CKError 0x15af87900: "Server Rejected Request" (15/2027); server message = "Default zone is not accessible in shared DB"; op = B085F7BA703D4A08; uuid = 87AEFB09-4386-4E43-81D7-971AAE8BA9E0; container ID = "iCloud.com.sfw-consulting.Family-List"&gt;
1
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101
Jun ’25
Using any SwiftData Query causes app to hang
I want to get to a point where I can use a small view with a query for my SwiftData model like this: @Query private var currentTrainingCycle: [TrainingCycle] init(/*currentDate: Date*/) { _currentTrainingCycle = Query(filter: #Predicate<TrainingCycle> { $0.numberOfDays > 0 // $0.startDate < currentDate && currentDate < $0.endDate }, sort: \.startDate) } The commented code is where I want to go. In this instance, it'd be created as a lazy var in a viewModel to have it stable (and not constantly re-creating the view). Since it was not working, I thought I could check the same view with a query that does not require any dynamic input. In this case, the numberOfDays never changes after instantiation. But still, each time the app tries to create this view, the app becomes unresponsive, the CPU usage goes at 196%, memory goes way high and the device heats up quickly. Am I holding it wrong? How can I have a dynamic predicate on a View in SwiftUI with SwiftData?
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235
Mar ’25
Using Observation class for multiple SwiftData Models
Greetings i have an app that uses three different SwiftData models and i want to know what is the best way to use the them accross the app. I though a centralized behaviour and i want to know if it a correct approach.First let's suppose that the first view of the app will load the three models using the @Enviroment that work with @Observation. Then to other views that add data to the swiftModels again with the @Environment. Another View that will use the swiftData models with graph and datas for average and min and max.Is this a corrent way? or i should use @Query in every view that i want and ModelContext when i add the data. @Observable class CentralizedDataModels { var firstDataModel: [FirstDataModel] = [] var secondDataModel: [SecondDataModel] = [] var thirdDataModel: [ThirdDataModel] = [] let context: ModelContext init(context:ModelContext) { self.context = context } }
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146
Jun ’25
'NSInvalidArgumentException', reason: 'Duplicate version checksums across stages detected.'
I have an iOS app using SwiftData with VersionedSchema. The schema is synchronized with an CloudKit container. I previously introduced some model properties that I have now removed, as they are no longer needed. This results in the current schema version being identical to one of the previous ones (except for its version number). This results in the following exception: 'NSInvalidArgumentException', reason: 'Duplicate version checksums across stages detected.' So it looks like we cannot have a newer schema version with an identical content to an older schema version. The intuitive way would be to re-add the old (identical) schema version to the end of the "schemas" list property in the SchemaMigrationPlan, in order to signal that it is the newest one, and to add a migration stage back to it, thus: public enum MySchemaMigrationPlan: SchemaMigrationPlan { public static var schemas: [any VersionedSchema.Type] { [ SchemaV100.self, SchemaV101.self, SchemaV100.self ] } public static var stages: [MigrationStage] { [ migrateV100toV101, migrateV101toV100 ] } However, I am not sure if this is the right way to go, as previously, as I wanted to write unit tests for schema migration and rollback, I tried defining an inverse for each migration stage, so that I could trigger a migration and a rollback from a unit test, which resulted in an exception saying that it is not supported to downgrade a VersionedSchema. I must admit that I solved the original problem by introducing a dummy model property that I will later remove. What would have been the correct approach?
1
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133
Jun ’25
ForEach and RandomAccessCollection
I'm trying to build a custom FetchRequest that I can use outside a View. I've built the following ObservableFetchRequest class based on this article: https://augmentedcode.io/2023/04/03/nsfetchedresultscontroller-wrapper-for-swiftui-view-models @Observable @MainActor class ObservableFetchRequest&lt;Result: Storable&gt;: NSObject, @preconcurrency NSFetchedResultsControllerDelegate { private let controller: NSFetchedResultsController&lt;Result.E&gt; private var results: [Result] = [] init(context: NSManagedObjectContext = .default, predicate: NSPredicate? = Result.E.defaultPredicate(), sortDescriptors: [NSSortDescriptor] = Result.E.sortDescripors) { guard let request = Result.E.fetchRequest() as? NSFetchRequest&lt;Result.E&gt; else { fatalError("Failed to create fetch request for \(Result.self)") } request.predicate = predicate request.sortDescriptors = sortDescriptors controller = NSFetchedResultsController(fetchRequest: request, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil) super.init() controller.delegate = self fetch() } private func fetch() { do { try controller.performFetch() refresh() } catch { fatalError("Failed to fetch results for \(Result.self)") } } private func refresh() { results = controller.fetchedObjects?.map { Result($0) } ?? [] } var predicate: NSPredicate? { get { controller.fetchRequest.predicate } set { controller.fetchRequest.predicate = newValue fetch() } } var sortDescriptors: [NSSortDescriptor] { get { controller.fetchRequest.sortDescriptors ?? [] } set { controller.fetchRequest.sortDescriptors = newValue.isEmpty ? nil : newValue fetch() } } internal func controllerDidChangeContent(_ controller: NSFetchedResultsController&lt;any NSFetchRequestResult&gt;) { refresh() } } Till this point, everything works fine. Then, I conformed my class to RandomAccessCollection, so I could use in a ForEach loop without having to access the results property. extension ObservableFetchRequest: @preconcurrency RandomAccessCollection, @preconcurrency MutableCollection { subscript(position: Index) -&gt; Result { get { results[position] } set { results[position] = newValue } } public var endIndex: Index { results.endIndex } public var indices: Indices { results.indices } public var startIndex: Index { results.startIndex } public func distance(from start: Index, to end: Index) -&gt; Int { results.distance(from: start, to: end) } public func index(_ i: Index, offsetBy distance: Int) -&gt; Index { results.index(i, offsetBy: distance) } public func index(_ i: Index, offsetBy distance: Int, limitedBy limit: Index) -&gt; Index? { results.index(i, offsetBy: distance, limitedBy: limit) } public func index(after i: Index) -&gt; Index { results.index(after: i) } public func index(before i: Index) -&gt; Index { results.index(before: i) } public typealias Element = Result public typealias Index = Int } The issue is, when I update the ObservableFetchRequest predicate while searching, it causes a Index out of range error in the Collection subscript because the ForEach loop (or a List loop) access a old version of the array when the item property is optional. List(request, selection: $selection) { item in VStack(alignment: .leading) { Text(item.content) if let information = item.information { // here's the issue, if I leave this out, everything works Text(information) .font(.callout) .foregroundStyle(.secondary) } } .tag(item.id) .contextMenu { if Item.self is Client.Type { Button("Editar") { openWindow(ClientView(client: item as! Client), id: item.id!) } } } } Is it some RandomAccessCollection issue or a SwiftUI bug?
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143
May ’25
defaultIsolation option and Core Data
When creating a new project in Xcode 26, the default for defaultIsolation is MainActor. Core Data creates classes for each entity using code gen, but now those classes are also internally marked as MainActor, which causes issues when accessing managed object from a background thread like this. Is there a way to fix this warning or should Xcode actually mark these auto generated classes as nonisolated to make this better? Filed as FB13840800. nonisolated struct BackgroundDataHandler { @concurrent func saveItem() async throws { let context = await PersistenceController.shared.container.newBackgroundContext() try await context.perform { let newGame = Item(context: context) newGame.timestamp = Date.now // Main actor-isolated property 'timestamp' can not be mutated from a nonisolated context; this is an error in the Swift 6 language mode try context.save() } } } Turning code gen off inside the model and creating it manually, with the nonisolated keyword, gets rid of the warning and still works fine. So I guess the auto generated class could adopt this as well? public import Foundation public import CoreData public typealias ItemCoreDataClassSet = NSSet @objc(Item) nonisolated public class Item: NSManagedObject { }
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111
Jun ’25
SwiftData and async functions
Hello, I recently published an app that uses Swift Data as its primary data storage. The app uses concurrency, background threads, async await, and BLE communication. Sadly, I see my app incurs many fringe crashes, involving EXC_BAD_ACCESS, KERN_INVALID_ADDRESS, EXC_BREAKPOINT, etc. I followed these guidelines: One ModelContainer that is stored as a global variable and used throughout. ModelContexts are created separately for each task, changes are saved manually, and models are not passed around. Threads with different ModelContexts might manipulate and/or read the same data simultaneously. I was under the impression this meets the usage requirements. I suspect perhaps the issue lies in my usage of contexts in a single await function, that might be paused and resumed on a different thread (although same execution path). Is that the case? If so, how should SwiftData be used in async scopes? Is there anything else particularly wrong in my approach?
4
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1.3k
Mar ’25
SwiftData Migration: Objects Created in Custom Migration Aren't Persisted or Queryable
Description: I'm experiencing a critical issue with SwiftData custom migrations where objects created during migration appear to be inserted successfully but aren't persisted or found by queries after migration completes. The migration logs show objects being created, but subsequent queries return zero results. Problem Details: I'm migrating from schema version V2 to V3, which involves: Renaming Person class to GroupData Keeping the same data structure but changing the class name Using a custom migration stage to copy data from old to new schema Migration Code: swift static let migrationV2toV3 = MigrationStage.custom( fromVersion: LinkMapV2.self, toVersion: LinkMapV3.self, willMigrate: { context in do { let persons = try context.fetch(FetchDescriptor<LinkMapV2.Person>()) print("Found (persons.count) Person objects to migrate") // ✅ Shows 11 objects for person in persons { let newGroup = LinkMapV3.GroupData( id: person.id, // Same UUID name: person.name, // ... other properties ) context.insert(newGroup) print("Inserted GroupData: '\(newGroup.name)'") // ✅ Confirms insertion } try context.save() // ✅ No error thrown print("Successfully migrated \(persons.count) objects") // ✅ Confirms save } catch { print("Migration error: \(error)") } }, didMigrate: { context in do { let groups = try context.fetch(FetchDescriptor<LinkMapV3.GroupData>()) print("Final GroupData count: \(groups.count)") // ❌ Shows 0 objects! } catch { print("Verification error: \(error)") } } ) Console Output: text === MIGRATION STARTED === Found 11 Person objects to migrate Migrating Person: 'Riverside of pipewall' with ID: 7A08C633-4467-4F52-AF0B-579545BA88D0 Inserted new GroupData: 'Riverside of pipewall' ... (all 11 objects processed) ... === MIGRATION COMPLETED === Successfully migrated 11 Person objects to GroupData === MIGRATION VERIFICATION === New GroupData count: 0 // ❌ PROBLEM: No objects found! What I've Tried: Multiple context approaches: Using the provided migration context Creating a new background context with ModelContext(context.container) Using context.performAndWait for thread safety Different save strategies: Calling try context.save() after insertions Letting SwiftData handle saving automatically Multiple save calls at different points Verification methods: Checking in didMigrate closure Checking in app's ContentView after migration completes Using both @Query and manual FetchDescriptor Schema variations: Direct V2→V3 migration Intermediate V2.5 schema with both classes Lightweight migration with @Attribute(originalName:) Current Behavior: Migration runs without errors Objects appear to be inserted successfully context.save() completes without throwing errors But queries in didMigrate and post-migration return empty results The objects seem to exist in a temporary state that doesn't persist Expected Behavior: Objects created during migration should be persisted and queryable Post-migration queries should return the migrated objects Data should be available in the main app after migration completes Environment: Xcode 16.0+ iOS 18.0+ SwiftData Swift 6.0+ Key Questions: Is there a specific way migration contexts should be handled for data to persist? Are there known issues with object persistence in custom migrations? Should we be using a different approach for class renaming migrations? Is there a way to verify that objects are actually being written to the persistent store? The migration appears to work perfectly until the verification step, where all created objects seem to vanish. Any guidance would be greatly appreciated! Additional Context from my investigation: I've noticed these warning messages during migration that might be relevant: text SwiftData.ModelContext: Unbinding from the main queue. This context was instantiated on the main queue but is being used off it. error: Persistent History (76) has to be truncated due to the following entities being removed: (Person) This suggests there might be threading or context lifecycle issues affecting persistence. Let me know if you need any additional information about my setup or migration configuration!
1
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107
Nov ’25
NSPersistentCloudKitContainer causes crash on watchOS when device is offline
Hi. I'm hoping someone might be able to help us with an issue that's been affecting our standalone watchOS app for some time now. We've encountered consistent crashes on Apple Watch devices when the app enters the background while the device is offline (i.e., no Bluetooth and no Wi-Fi connection). Through extensive testing, we've isolated the problem to the use of NSPersistentCloudKitContainer. When we switch to NSPersistentContainer, the crashes no longer occur. Interestingly, this issue only affects our watchOS app. The same CloudKit-based persistence setup works reliably on our iOS and macOS apps, even when offline. This leads us to believe the issue may be specific to how NSPersistentCloudKitContainer behaves on watchOS when the device is disconnected from the network. We're targeting watchOS 10 and above. We're unsure if this is a misconfiguration on our end or a potential system-level issue, and we would greatly appreciate any insight or guidance.
2
0
134
Jun ’25
SwiftData Background Fetching?
Hi, I am experiencing main thread freezes from fetching on Main Actor. Attempting to move the function to a background thread, but whenever I reference the TestModel in a nonisolated context or in another model actor, I get this warning: Main actor-isolated conformance of 'TestModel' to 'PersistentModel' cannot be used in actor-isolated context; this is an error in the Swift 6 language mode Is there a way to do this correctly? Recreation, warning on line 13: class TestModel { var property: Bool = true init() {} } struct SendableTestModel: Sendable { let property: Bool } @ModelActor actor BackgroundActor { func fetch() throws -> [SendableTestModel] { try modelContext.fetch(FetchDescriptor<TestModel>()).map { SendableTestModel(property: $0.property) } } }
1
0
141
Jul ’25
CloudKit container name
I have a new app I am working on, it uses, a container id like com.me.mycompany.FancyApp.prod, the description in the app is My Fancy App. When I deploy the app via TestFlight on a real device, the sync seems to work, but when I view iCloud->Storage-List, I see my app icon, and the name "prod". Where did the name prod come from? It should be My Fancy App, which is the actual name of the App.
3
0
163
Jan ’26
CoreData CloudKit Sync not working between iOs and MacOS
Hi All, I work on a cross platform app, iOS/macOS. All devises on iOS could synchronize data from Coredata : I create a client, I see him an all iOS devices. But when I test on macOs (with TestFlight) the Mac app could not get any information from iOs devices. On Mac, cloud drive is working because I could download and upload documents and share it between all devices, so the account is working but with my App on MacOS, there is no synchronisation. idea????
2
0
1.2k
Sep ’25