SwiftUI/SwiftData view deep in the hierarchy looses model container

Question

yukas OP

Created Apr ’24

Replies 4

Boosts 0

Participants 3

iPad mini device with iPadOS 17.4.1.

I get this failure on iPad mini device exclusively. I have universal app and I doesn't get this error neither on iPhone or any simulator or macOS. I tried to reset the iPad, still getting the error.

The error happens when I send the app to background from the particular app screen.

Here is the error:

error: Store failed to load.
<NSPersistentStoreDescription: 0x3004b4bd0> (type: SQLite, url: file:///dev/null) with error = Error Domain=NSCocoaErrorDomain Code=134060 

"A Core Data error occurred."
UserInfo={NSLocalizedFailureReason=The configuration named 'default' does not contain any entities.} with userInfo {
    NSLocalizedFailureReason = "The configuration named 'default' does not contain any entities.";
}

What error says is that it loaded the store from file:///dev/null, which is wrong. Basically it looses the model container which is added via modelContaner modificator to the root view.

The error get caused particularly by the @Environment(\.modelContext) private var modelContext call in the view on which the failure occurs. This view is deep in the view hierarchy, and it get's created in the navigationDestination block.

I fixed the error by supplying modelContainer one more time right on the view:

.navigationDestination(for: File.self) { file in
    FileEditor(file: file)
        .modelContainer(FolderService.modelContainer)
}

I wonder, why can it loose the model container which is supplied on the root view?

Boost

Answer 1

jhokit OP

Apr ’24

Seeing the same bug on 17.4.1 iPads too. Can't reproduce on Mac or iPhone

0

Answer 2

jhokit OP

May ’24

I found that I had to remove ALL usage of @Environment(.modelContext) private var modelContext to eliminate all SwiftUI/SwiftData background crashes since 17.4. See https://developer.apple.com/forums/thread/744194?answerId=788019022#788019022

0

Answer 3

malc OP

Aug ’24

Can you show how you are setting the container on the root view and how you are initializing your container. Maybe you are accidentally initing it twice.

0

Answer 4

jhokit OP

Aug ’24

@malc Interesting idea. I don't think I'm initing twice. A SwiftData engineer acknowledged the corrupted modelContext environment variable as a known bug.

Container initialized in a singleton...


@MainActor struct DataCenter {
    static var shared:DataCenter = DataCenter.init()

    public let container: ModelContainer
    public let context: ModelContext

    init() {
        let schema = Schema([
            Folder.self,
            Reminder.self,
            DateReminder.self,
            LocationReminder.self
        ])
        
        container = try! ModelContainer(for: schema, configurations: [ModelConfiguration(isStoredInMemoryOnly: false)])
        context = container.mainContext
    }
}

Setting the container...

  WindowGroup {
            ContentView()
        }
        .modelContainer(DataCenter.shared.container)

I don't reference the modelContext environment variable anywhere. In code that needs the context, I always reference the singleton...


        let folder = Folder(name: newFolderName)
        DataCenter.shared.context.insert(folder)

It's been working fine, until iOS 18 came along. But I think my many problems with SwiftData in 18 have nothing at all to do with this container usage. But I've been wrong before.

0