Hi,
I'm getting a very odd error log in my SwiftData setup for an iOS app. It is implemented to support schema migration. When starting the app, it simply prints the following log twice (seems to be dependent on how many migration steps, I have two steps in my sample code):
CoreData: error: Attempting to retrieve an NSManagedObjectModel version checksum while the model is still editable. This may result in an unstable verison checksum. Add model to NSPersistentStoreCoordinator and try again.
(Yes there is a mistyped word "verison", this is exactly the log)
The code actually fully works. But I have neither CloudKit configured, nor is this app in Production yet. I'm still just developing.
Here is the setup and code to reproduce the issue.
Development mac version: macOS 15.5
XCode version: 16.4
iOS Simulator version: 18.5
Real iPhone version: 18.5
Project name: SwiftDataDebugApp
SwiftDataDebugApp.swift:
import SwiftUI
import SwiftData
@main
struct SwiftDataDebugApp: App {
var sharedModelContainer: ModelContainer = {
let schema = Schema([
Item.self,
])
let modelConfiguration = ModelConfiguration(schema: schema, isStoredInMemoryOnly: false, allowsSave: true)
do {
return try ModelContainer(for: schema, migrationPlan: ModelMigraitonPlan.self, configurations: [modelConfiguration])
} catch {
fatalError("Could not create ModelContainer: \(error)")
}
}()
var body: some Scene {
WindowGroup {
ContentView()
}
.modelContainer(sharedModelContainer)
}
}
Item.swift:
import Foundation
import SwiftData
typealias Item = ModelSchemaV2_0_0.Item
enum ModelSchemaV1_0_0: VersionedSchema {
static var versionIdentifier = Schema.Version(1, 0, 0)
static var models: [any PersistentModel.Type] {
[Item.self]
}
@Model
final class Item {
var timestamp: Date
init(timestamp: Date) {
self.timestamp = timestamp
}
}
}
enum ModelSchemaV2_0_0: VersionedSchema {
static var versionIdentifier = Schema.Version(2, 0, 0)
static var models: [any PersistentModel.Type] {
[Item.self]
}
@Model
final class Item {
var timestamp: Date
var tags: [Tag] = []
init(timestamp: Date, tags: [Tag]) {
self.timestamp = timestamp
self.tags = tags
}
}
}
enum ModelMigraitonPlan: SchemaMigrationPlan {
static var schemas: [any VersionedSchema.Type] {
[ModelSchemaV1_0_0.self]
}
static var stages: [MigrationStage] {
[migrationV1_0_0toV2_0_0]
}
static let migrationV1_0_0toV2_0_0 = MigrationStage.custom(
fromVersion: ModelSchemaV1_0_0.self,
toVersion: ModelSchemaV2_0_0.self,
willMigrate: nil,
didMigrate: { context in
let items = try context.fetch(FetchDescriptor<ModelSchemaV2_0_0.Item>())
for item in items {
item.tags = Array(repeating: "abc", count: Int.random(in: 0...3)).map({ Tag(value: $0) })
}
try context.save()
}
)
}
Tag.swift:
import Foundation
struct Tag: Codable, Hashable, Comparable {
var value: String
init(value: String) {
self.value = value
}
static func < (lhs: Tag, rhs: Tag) -> Bool {
return lhs.value < rhs.value
}
static func == (lhs: Tag, rhs: Tag) -> Bool {
return lhs.value == rhs.value
}
func hash(into hasher: inout Hasher) {
hasher.combine(value)
}
}
ContentView.swift:
import SwiftUI
import SwiftData
struct ContentView: View {
@Environment(\.modelContext) private var modelContext
@Query private var items: [Item]
var body: some View {
VStack {
List {
ForEach(items) { item in
VStack(alignment: .leading) {
Text(item.timestamp, format: Date.FormatStyle(date: .numeric, time: .standard))
HStack {
ForEach(item.tags, id: \.hashValue) { tag in
Text("\(tag.value)")
}
}
}
}
.onDelete(perform: deleteItems)
}
Button("Add") {
addItem()
}
.padding(.top)
}
}
private func addItem() {
withAnimation {
let newItem = Item(timestamp: Date(), tags: [Tag(value: "Hi")])
modelContext.insert(newItem)
}
do {
try modelContext.save()
} catch {
print("Error saving add: \(error.localizedDescription)")
}
}
private func deleteItems(offsets: IndexSet) {
withAnimation {
for index in offsets {
modelContext.delete(items[index])
}
}
do {
try modelContext.save()
} catch {
print("Error saving delete: \(error.localizedDescription)")
}
}
}
#Preview {
ContentView()
.modelContainer(for: Item.self, inMemory: true)
}
I hope someone can help, couldn't find anything related to this log at all.