在独立的 watchOS 应用上实现核心数据

Question

As I know, we can use Core Data on Apple Watch apps. So an independent watchOS app can have it's own persistent store. But when we creating a project for watchOS app, there is no option to use core data (like when we creating a project for an iOS app)

So, how to implement Core Data on an independent watchOS app?

I've copied this code from an iOS app (which uses Core Data) and pasted it to the ExtensionDelegate of my independent SwiftUI watchOS app

 // MARK: - Core Data stack

    lazy var persistentContainer: NSPersistentContainer = {
        /*
         The persistent container for the application. This implementation
         creates and returns a container, having loaded the store for the
         application to it. This property is optional since there are legitimate
         error conditions that could cause the creation of the store to fail.
        */
        let container = NSPersistentContainer(name: "CoreDataToDo")
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.

                /*
                 Typical reasons for an error here include:
                 * The parent directory does not exist, cannot be created, or disallows writing.
                 * The persistent store is not accessible, due to permissions or data protection when the device is locked.
                 * The device is out of space.
                 * The store could not be migrated to the current model version.
                 Check the error message to determine what the actual problem was.
                 */
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
        return container
    }()

    // MARK: - Core Data Saving support

    func saveContext () {
        let context = persistentContainer.viewContext
        if context.hasChanges {
            do {
                try context.save()
            } catch {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                let nserror = error as NSError
                fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
            }
        }
    }

So what should I do next?
or am I already doing this wrong?

Please help me. I've tried so hard to find how to do this. But I can't find any good solutions because previously there were no independent watchOS apps so most of the developers didn't create a separate persistent stores for the watchOS apps.
So please help me.
Thanks.

Answer 1

You need to make sure you have an xcdatamodeld file as well, then you should be pretty much good to go. See my answer to this question for how to pass your managed object context to View s and how to properly set up the WKHostingController subclass.

Answer 2

Check this video about CoreData FetchRequest for WatchOS in SwiftUI by schwiftyUI