The Java Swing and AWT MVC model made it easy to develop complex UIs with data interactions that were not described readily in a nested layer that SwiftUI demands. The implicit update model of SwiftUI greatly complicates development of applications that often requires nested components to have to know too much about other components and other structures than their own, because button events and other user interactions cannot readily alter state across layers. A button push on one component then has to be knowledgable about state in other components which have to have that state represented as @State or @Binding etc. and this causes all kinds of wiring to be spread all over the place rather than have a more centralized "state management function" that would be able to look at the world and synchronize the UIs state across changes. The fact that the compiler get's lost in the weeds when types and signatures don't match in deeper component structures doesn't help because it makes it doubly hard to do refactoring to raise and lower state management within the structure readily, because the compiler just cannot simply tell you that a function or constructor signature is no longer correct.

Hi, I'm considering using the new SwiftData class inheritance for a new app I'm building. I have a few questions: Is it working well enough for production? I have a number of different object types in my app. Some of them are very similar, and there's always a balance to be struck when it comes to splitting them into different types using class inheritance. Are there some good advice on when to use multiple classes instead of squeezing my object types into a single class? Is there advice against using class inheritance in multiple levels (3-4)? Claes

Hi, I’m using SwiftData with an @Observable DatabaseManager class that is shared between my app and a widget. This class is located inside a Swift package and looks roughly like this: public final class DatabaseManager { public static let shared = DatabaseManager() private init() { let groupID = "group.com.yourcompany.myApp" let config = ModelConfiguration(groupContainer: .identifier(groupID)) let c = try! ModelContainer(for: MyModel.self, configurations: config) self.container = c self.modelContext = c.mainContext } public private(set) var container: ModelContainer public private(set) var modelContext: ModelContext } In the main app, I inject the container and context like this: struct MyApp: App { var body: some Scene { WindowGroup { ContentView() .modelContainer(DatabaseManager.shared.container) .modelContext(DatabaseManager.shared.modelContext) } } } Both the widget and the main app import the same package, and both use DatabaseManager.shared for reading and writing objects. The problem: When the widget updates an object using an AppIntent, the change is not reflected in the main app unless I fully terminate and relaunch it. If I just bring the app back to the foreground, it still shows stale data. Is there a recommended way to make the main app observe or reload SwiftData changes that were made in the widget (via the same shared app group and container)? I’m already using .modelContainer(...) and .modelContext(...) in the app, and everything else works fine — it’s just the syncing that doesn’t happen unless I force-relaunch the app. Thanks!

Hi, I keep trying to use transformable to store an array of strings with SwiftData, and I can see that it is activating the transformer, but it keeps saying that I am still using NSArray instead of NSData. *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unacceptable type of value for attribute: property = "category"; desired type = NSData; given type = Swift.__SwiftDeferredNSArray; value = ( yo, gurt ).' terminating due to uncaught exception of type NSException CoreSimulator 1010.10 - Device: iPhone 16 18.0 (6879535B-3174-4025-AD37-ED06E60291AD) - Runtime: iOS 18.0 (22A3351) - DeviceType: iPhone 16 Message from debugger: killed @Model class MyModel: Identifiable, Equatable { @Attribute(.transformable(by: StringArrayTransformer.self)) var category: [String]? @Attribute(.transformable(by: StringArrayTransformer.self)) var amenities: [String]? var image: String? var parentChunck: HenricoPostDataChunk_V1? init(category: [String]?, amenities: [String]?) { self.category = category self.amenities = amenities } } class StringArrayTransformer: ValueTransformer { override func transformedValue(_ value: Any?) -> Any? { print(value) guard let array = value as? [String] else { return nil } let data = try? JSONSerialization.data(withJSONObject: array, options: []) print(data) return data } override func reverseTransformedValue(_ value: Any?) -> Any? { guard let data = value as? Data else { return nil } let string = (try? JSONSerialization.jsonObject(with: data, options: [])) as? [String] print(string) return string } override class func transformedValueClass() -> AnyClass { return NSData.self } override class func allowsReverseTransformation() -> Bool { return true } static func register() { print("regitsering") ValueTransformer.setValueTransformer(StringArrayTransformer(), forName: .stringArrayTransformerName) } } extension NSValueTransformerName { static let stringArrayTransformerName = NSValueTransformerName("StringArrayTransformer") }

I have a SwiftUI document-based app that for the sake of this discussion stores accounting information: chart of accounts, transactions, etc. Each document is backed by a SwiftData DB. I'd like to incorporate search into the app so that users can find transactions matching certain criteria, so I went to Core Spotlight. Indexing & search within the app seem to work well. The issue is that Spotlight APIs appear to be App based & not Document based. I can't find a way to separate Spotlight data by document. I've tried having each document maintain a UUID as a document-specific identifier and include the identifier in every CSSearchableItem. When performing a query I filter the results with CSUserQueryContext.filterQueries that filter by the document identifier. That works to limit results to the specific file for search operations. Index updates via CSSearchableIndexDelegate.reindex* methods seem to be App-centric. A user may have file #1 open, but the delegate is being asked to update CSSearchableItems for IDs in other files. Is there a proper way to use Spotlight for in-app search with a document-based app? Is there a way to keep Spotlight-indexed data local within the app & not make it available across the system? I.e. I'd like to search within the app only. System-level searches should not surface this data.

I am struggling with exactly how to set up SwiftData relationships, beyond the single relationship model... Let's say I have a school. Each school offers a set of classes. Each class is taught by one teacher and attended by several students. Teachers may teach more than one class, but only at one school. Similarly students may attend more than one class, but only at one school. Classes themselves may be offered at more than one school. Can someone create a class for School, SchoolClass, Teacher, and Student with id, name, and relationships... I have tried it unsuccessfully about 10 different ways at this point. My most recent is below... I am struggling getting beyond a school listing in the app, and I'll cross that bridge next. I am just wondering if all the trouble I am having is because I am not smart with the class definitions. And wondering if this is to complex for SwiftData and CoreData is the requirement. This is not a real app, just my way of really trying to get a handle on Swift Data models and Navigation. I am very new to Swift, and will take any and all suggestions with enthusiasm! Thanks for taking the time. import Foundation import SwiftData @Model class School: Identifiable { var id: UUID = UUID() var name: String var mascot: String var teachers: [Teacher] var schoolClasses: [SchoolClass] init (name: String, mascot: String = "", teachers: [Teacher] = [], schoolClasses: [SchoolClass] = []) { self.name = name self.mascot = mascot self.teachers = teachers } class SchoolClass: Identifiable { var id: UUID = UUID() var name: String var teacher: Teacher? var students: [Student] = [] init (name: String, teacher: Teacher? = nil, students: [Student] = []) { self.name = name self.teacher = teacher self.students = students } } class Teacher: Identifiable { var id: UUID = UUID() var name: String var tenured: Bool var school: School? var students: [Student] = [] init (name: String, tenured: Bool = false, students: [Student] = []) { self.name = name self.tenured = tenured self.students = students } } class Student: Identifiable { var id: UUID = UUID() var name: String var grade: Int? var teacher: Teacher? init (name: String, grade: Int? = nil, teacher: Teacher? = nil) { self.name = name self.grade = grade self.teacher = teacher } } }

Any idea what this message means? I assume it's coming from CloudKit, but the application seems to store and retrieve data properly.

This is not a question but more of a hint where I was having trouble with. In my SwiftData App I wanted to move from Swift 5 to Swift 6, for that, as recommended, I stayed in Swift 5 language mode and set 'Strict Concurrency Checking' to 'Complete' within my build settings. It marked all the places where I was using predicates with the following warning: Type '' does not conform to the 'Sendable' protocol; this is an error in the Swift 6 language mode I had the same warnings for SortDescriptors. I spend quite some time searching the web and wrapping my head around how to solve that issue to be able to move to Swift 6. In the end I found this existing issue in the repository of the Swift Language https://github.com/swiftlang/swift/issues/68943. It says that this is not a warning that should be seen by the developer and in fact when turning Swift 6 language mode on those issues are not marked as errors. So if anyone is encountering this when trying to fix all issues while staying in Swift 5 language mode, ignore those, fix the other issues and turn on Swift 6 language mode and hopefully they are gone.

I have an Apple app that uses SwiftData and icloud to sync the App's data across users' devices. Everything is working well. However, I am facing the following issue: SwiftData does not support public sharing of the object graph with other users via iCloud. How can I overcome this limitation without stopping using SwiftData? Thanks in advance!

I'm building a SwiftUI app using SwiftData. In my app I have a Customer model with an optional codable structure Contact. Below is a simplified version of my model: @Model class Customer { var name: String = "" var contact: Contact? init(name: String, contact: Contact? = nil) { self.name = name self.contact = contact } struct Contact: Codable, Equatable { var phone: String var email: String var allowSMS: Bool } } I'm trying to query all the Customers that have a contact with @Query. For example: @Query(filter: #Predicate<Customer> { customer in customer.contact != nil }) var customers: [Customer] However no matter how I set the predicate I always get an error: BugDemo crashed due to an uncaught exception NSInvalidArgumentException. Reason: keypath contact not found in entity Customer. How can I fix this so that I'm able to filter by contact not nil in my Model?

I tried to use the .deny deleteRule but it seems to have no effect. The toolbar button adds an item with a relationship to a category to the context. Swiping on the category deletes the category even though an item is referencing the category. There is also no error thrown when saving the context. It is as if the deleteRule was not there. For other deleteRules like .cascade, the provided sample code works as expected. import SwiftUI import SwiftData @Model class Category { var name: String @Relationship(deleteRule: .deny) var items: [Item] = [] init(name: String) { self.name = name } } @Model class Item { var name: String var category: Category? init(name: String, category: Category) { self.name = name self.category = category } } struct DenyDeleteRule: View { @Environment(\.modelContext) private var modelContext @Query private var categories: [Category] @Query private var items: [Item] var body: some View { List { Section("Items") { ForEach(items) { item in Text(item.name) } } Section("Categories") { ForEach(categories) { category in VStack(alignment: .leading) { Text(category.name).bold() ForEach(category.items) { item in Text("• \(item.name)") } } } .onDelete(perform: deleteCategory) } } .toolbar { Button("Add Sample") { let category = Category(name: "Sample") let item = Item(name: "Test Item", category: category) modelContext.insert(item) } } } func deleteCategory(at offsets: IndexSet) { for index in offsets { let category = categories[index] modelContext.delete(category) do { try modelContext.save() } catch { print(error) } } } } #Preview { NavigationStack { DenyDeleteRule() } .modelContainer(for: [Item.self, Category.self], inMemory: true) }

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?

When I update a variable inside my model that is marked @Transient, my view does not update with this change. Is this normal? If I update a non-transient variable inside the model at the same time that I update the transient one, then both changes are propagated to my view. Here is an example of the model: @Model public class WaterData { public var target: Double = 3000 @Transient public var samples: [HKQuantitySample] = [] } Updating samples only does not propagate to my view.

If I set my build settings "default actor isolation" to MainActor, how do my @ModelActor actors and model classes need to look like ? For now, I am creating instances of my @ModelActor actors and passing my modelContext container and processing all data there. Everything stays in this context. No models are transferred back to MainActor. Now, after changing my project settings, I am getting a huge amount of warnings. Do I need to set all my model classes to non-isolated and the @ModelActor actor as well? Is there any new sample code to cover this topic ... did not find anything for now. Thanks in advance, Marc

I would like to have a SwiftData predicate that filters against an array of PersistentIdentifiers. A trivial use case could filtering Posts by one or more Categories. This sounds like something that must be trivial to do. When doing the following, however: let categoryIds: [PersistentIdentifier] = categoryFilter.map { $0.id } let pred = #Predicate<Post> { if let catId = $0.category?.persistentModelID { return categoryIds.contains(catId) } else { return false } } The code compiles, but produces the following runtime exception (XCode 26 beta, iOS 26 simulator): 'NSInvalidArgumentException', reason: 'unimplemented SQL generation for predicate : (TERNARY(item != nil, item, nil) IN {}) (bad LHS)' Strangely, the same code works if the array to filter against is an array of a primitive type, e.g. String or Int. What is going wrong here and what could be a possible workaround?

We are trying to solve for the following condition with SwiftData + CloudKit: Lots of data in CloudKit Perform "app-reset" to clear data & App settings and start fresh. Reset data models with try modelContext.delete(model:_) myModel.count() confirms local deletion (0 records); but iCloud Console shows expectedly slow process to delete. Old CloudKit data is returning during the On Boarding process. Questions: • Would making a new iCloud Zone for each reset work around this, as the new zone would be empty? We're having trouble finding details about how to do this with SwiftData. • Would CKSyncEngine have a benefit over the default SwiftData methods? Open to hearing if anyone has experienced a similar challenge and how you worked around it!

Hi, I am building an iOS app with SwiftUI and SwiftData for the first time and I am experiencing a lot of difficulty with this error: Thread 44: Fatal error: Never access a full future backing data - PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(backing: SwiftData.PersistentIdentifier.PersistentIdentifierBacking.managedObjectID(<ID> <x-coredata://<UUID>/MySwiftDataModel/p1>)), backing: SwiftData.PersistentIdentifier.PersistentIdentifierBacking.managedObjectID(<ID> <x-coredata://<UUID>/MySwiftDataModel/p1>)) with Optional(<UUID>) I have been trying to figure out what the problem is, but unfortunately I cannot find any information in the documentation or on other sources online. My only theory about this error is that it is somehow related to fetching an entity that has been created in-memory, but not yet saved to the modelContext in SwiftData. However, when I am trying to debug this, it's not clear this is the case. Sometimes the error happens, sometimes it doesn't. Saving manually does not always solve the error. Therefore, it would be extremely helpful if someone could explain what this error means and whether there are any best practices to do with SwiftData, or some pitfalls to avoid (such as wrapping my model context into a repository class). To be clear, this problem is NOT related to one area of my code, it happens throughout my app, at unpredictable places and time. Given that there is very little information related to this error, I am at a loss at how to make sure that this never happens. This question has been asked on the forum here as well as on StackOverflow, Reddit (can't link that here), but none of the answers worked for me. For reference, my models generally look like this: import Foundation import SwiftData @Model final class MySwiftDataModel { // Stable cross-device identity @Attribute(.unique) var uuid: UUID var someNumber: Int var someString: String @Relationship(deleteRule: .nullify, inverse: \AnotherSwiftDataModel.parentModel) var childModels: [AnotherSwiftDataModel] init(uuid: UUID = UUID(), someNumber: Int = 1, someString: String = "Some", childModels: [AnotherSwiftDataModel] = []) { self.uuid = uuid self.someNumber = someNumber self.someString = someString self.childModels = childModels } func addChildModel(model: AnotherSwiftDataModel) { self.childModels.append(model) } func removeChildModel(by id: PersistentIdentifier) { self.childModels = self.childModels.filter { $0.id != id } } } and the child model: import Foundation import SwiftData @Model final class AnotherSwiftDataModel { // Stable cross-device identity @Attribute(.unique) var uuid: UUID var someNumber: Int var someString: String var parentModel: MySwiftDataModel? init(uuid: UUID = UUID(), someNumber: Int = 1, someString: String = "Some") { self.uuid = uuid self.someNumber = someNumber self.someString = someString } } For now, you can assume I am not using CloudKit - i know for a fact the error is unrelated to CloudKit, because it happens when I am not using CloudKit (so I do not need to follow CloudKit's requirements for model design, such as nullable values etc). As I said, the error surfaces at different times - sometimes during assignments, a lot of times during deletions of related models, etc. Could you please explain what I am doing wrong and how I can make sure that this error does not happen? What are the architectural patterns that work best for SwiftData in this case? Do you have any examples of things I should avoid? Thanks

I have encountered the following error and reduced my code to the minimum necessary to reliably reproduce this error. Fatal error: Duplicate keys of type 'AnyHashable2' 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. It occurs when instances of a swiftdata model are inserted (the error occurs reliably when inserting five or more instances. Fewer insertions seems to make the error either more rare or go away entirely) and a Picker with .menu pickerStyle is present. Any of the following changes prevents the error from occuring: adding id = UUID() to the Item class removing .tag(item) in the picker content using any pickerStyle other than .menu using an observable class instead of a swiftdata class I would greatly appreciate if anyone knows what exactly is going on here. Tested using XCode Version 16.4 (16F6), iPhone 16 Pro iOS 18.5 Simulator and iPhone 15 Pro iOS 18.5 real device. import SwiftUI import SwiftData @Model class Item { var name: String init(name: String) { self.name = name } } struct DuplicateKeysErrorView: View { @Environment(\.modelContext) private var modelContext @Query(sort: \Item.name) private var items: [Item] @State var selection: Item? = nil var body: some View { List { Picker("Picker", selection: $selection) { Text("Nil").tag(nil as Item?) ForEach(items) { item in Text(item.name).tag(item) } } .pickerStyle(.menu) Button("Add 5 items") { modelContext.insert(Item(name: UUID().uuidString)) modelContext.insert(Item(name: UUID().uuidString)) modelContext.insert(Item(name: UUID().uuidString)) modelContext.insert(Item(name: UUID().uuidString)) modelContext.insert(Item(name: UUID().uuidString)) } } .onAppear { try! modelContext.delete(model: Item.self) } } } #Preview { DuplicateKeysErrorView() .modelContainer(for: Item.self) }

I have used core data before via the model editor. This is the first time I'm using swift data and that too with CloudKit. Can you tell me if the following model classes are correct? I have an expense which can have only one sub category which in turn belongs to a single category. Here are my classes... // Expense.swift // Pocket Expense Diary // // Created by Neerav Kothari on 16/05/25. // import Foundation import SwiftData @Model class Expense { @Attribute var expenseDate: Date? = nil @Attribute var expenseAmount: Double? = nil @Attribute var expenseCategory: Category? = nil @Attribute var expenseSubCategory: SubCategory? = nil var date: Date { get { return expenseDate ?? Date() } set { expenseDate = newValue } } var amount: Double{ get { return expenseAmount ?? 0.0 } set { expenseAmount = newValue } } var category: Category{ get { return expenseCategory ?? Category.init(name: "", icon: "") } set { expenseCategory = newValue } } var subCategory: SubCategory{ get { return expenseSubCategory ?? SubCategory.init(name: "", icon: "") } set { expenseSubCategory = newValue } } init(date: Date, amount: Double, category: Category, subCategory: SubCategory) { self.date = date self.amount = amount self.category = category self.subCategory = subCategory } } // // Category.swift // Pocket Expense Diary // // Created by Neerav Kothari on 16/05/25. // import Foundation import SwiftData @Model class Category { @Attribute var categoryName: String? = nil @Attribute var categoryIcon: String? = nil var name: String { get { return categoryName ?? "" } set { categoryName = newValue } } var icon: String { get { return categoryIcon ?? "" } set { categoryIcon = newValue } } @Relationship(inverse: \Expense.expenseCategory) var expenses: [Expense]? = [] init(name: String, icon: String) { self.name = name self.icon = icon } } // SubCategory.swift // Pocket Expense Diary // // Created by Neerav Kothari on 16/05/25. // import Foundation import SwiftData @Model class SubCategory { @Attribute var subCategoryName: String? = nil @Attribute var subCategoryIcon: String? = nil var name: String { get { return subCategoryName ?? "" } set { subCategoryName = newValue } } var icon: String { get { return subCategoryIcon ?? "" } set { subCategoryIcon = newValue } } @Relationship(inverse: \Expense.expenseSubCategory) var expenses: [Expense]? = [] init(name: String, icon: String) { self.name = name self.icon = icon } } The reason why I have wrappers is the let the existing code (before CloudKit was integrated), work. In future versions I plan to query expenses even via category or sub category. I particularly doubt for the relationship i have set. should there be one from category to subcategory as well?

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 } }