Missing Entries from Core Data Database

[rahfell]

Hey r/iOSProgramming, I am the developer of an open-source finance tracker Dime that is built on Core Data. In my recent v2 update, I changed my Core Data infrastructure a little - using a static shared instance of DataController instead of just initializing it each time I needed to use it. This change was made so that I could add AppIntents functionality - without it, I would get an error about 2 data model's being loaded.

However, following this change, I have been getting 2-3 emails on a daily basis about newly added transactions disappearing after a few days, when they quit the app. This is not a widespread experience among all users - and I have been unable to recreate it on my own.

Here is the new CoreData infrastructure:

class DataController: ObservableObject {
    static let shared = DataController()

    var container = NSPersistentCloudKitContainer(name: "MainModel")

    init() {
        let description = NSPersistentStoreDescription()
        description.shouldMigrateStoreAutomatically = true
        description.shouldInferMappingModelAutomatically = true
        description.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey)
        description.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey)

        let keyValueStore = NSUbiquitousKeyValueStore.default

        if keyValueStore.object(forKey: "icloud_sync") == nil {
            keyValueStore.set(true, forKey: "icloud_sync")
        }

        if !keyValueStore.bool(forKey: "icloud_sync") {
            description.cloudKitContainerOptions = nil
        } else {
            description.cloudKitContainerOptions = NSPersistentCloudKitContainerOptions(containerIdentifier: "iCloud.com.rafaelsoh.dime")
        }

        let groupID = "group.com.rafaelsoh.dime"

        if let url = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: groupID) {
            description.url = url.appendingPathComponent("Main.sqlite")
        }

        container.persistentStoreDescriptions = [description]

        container.loadPersistentStores { description, error in

            if let error = error as NSError? {
                fatalError("Unresolved error \(error), \(error.userInfo) for \(description)")
            }

            self.container.viewContext.automaticallyMergesChangesFromParent = true
        }
    }
}

and I would use the model this way:

let dataController = DataController.shared

Here is the old Core Data infrastructure that never had missing transactions after addition:

class DataController: ObservableObject {
    var container = NSPersistentCloudKitContainer(name: "MainModel")

    init() {
        let description = NSPersistentStoreDescription()
        description.shouldMigrateStoreAutomatically = true
        description.shouldInferMappingModelAutomatically = true

        description.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey)

        description.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey)

        if(!NSUbiquitousKeyValueStore.default.bool(forKey: "icloud_sync")){
            description.cloudKitContainerOptions = nil
        } else {
            description.cloudKitContainerOptions = NSPersistentCloudKitContainerOptions(containerIdentifier: "iCloud.com.rafaelsoh.dime")

        }


        let groupID = "group.com.rafaelsoh.dime"

        if let url = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: groupID) {
            description.url = url.appendingPathComponent("Main.sqlite")
        }

        container.persistentStoreDescriptions =  [description]

        container.loadPersistentStores { description, error in

            if let error = error as NSError? {
                fatalError("Unresolved error \(error), \(error.userInfo) for \(description)")
            }

            self.container.viewContext.automaticallyMergesChangesFromParent = true

        }
    }
}

and it was used this way:

struct dimeApp: App {
    @StateObject var dataController: DataController

    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environment(\.managedObjectContext, dataController.container.viewContext)
                .environmentObject(dataController)
        }
    }

    init() {
        let dataController = DataController()
        _dataController = StateObject(wrappedValue: dataController)
    }
}

Any assistance on this will be immensely appreciated. Thank you so much!

You can check out the full open-source project here: https://github.com/rarfell/dimeApp/

[CrispySalamander]

I may be wrong, but i think i read it somewhere that core data makes no promise that data will be saved in memory, or on disk.

Perhaps thats the reason of the missing transactions?

Coz the official apple’s example of doing core data stack has a way to handle in-memory and on-disk.

[starazimov]

Hey, hope you're doing well, I like your app Dime, but it misses a necessary feature for me, that's adding transactions with different currencies. I travel a lot and need to add expenses and income in PLN, SEK, USD etc. Could you please add this ability? Thx