在独立的 watchOS 应用程序上实现 Core Data

Question

据我所知，我们可以在 Apple Watch 应用上使用 Core Data。因此，独立的 watchOS 应用程序可以拥有自己的持久存储。但是当我们为 watchOS 应用程序创建项目时，没有选择使用核心数据（就像我们为 iOS 应用程序创建项目时一样）

那么，如何在独立的watchOS应用上实现Core Data呢？

我已从 iOS 应用程序（使用 Core Data）复制此代码并将其粘贴到ExtensionDelegate我的独立 SwiftUI watchOS 应用程序中

 // 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)")
            }
        }
    }

那么接下来我应该做什么呢？
或者我已经做错了？

请帮我。我非常努力地寻找如何做到这一点。但我找不到任何好的解决方案，因为以前没有独立的 watchOS 应用程序，因此大多数开发人员没有为 watchOS 应用程序创建单独的持久存储。
所以请帮助我。
谢谢。

Answer 1

您需要确保您xcdatamodeld也有一个文件，然后就可以开始了。请参阅我对此问题的回答，了解如何将托管对象上下文传递给Views 以及如何正确设置WKHostingController子类。