核心数据+ CloudKit-iOS和watchOS伴侣应用之间的共享

Question

在我的应用中，我将数据与核心数据一起存储。最近，我发现了Apple在WWDC19中引入的新功能，该功能允许核心数据与CloudKit一起使用。我刚刚为我的应用启用了cloudKit，并使用了NSPersistentCloudKitContainer而不是NSPersistentContainer，一切都已设置！我所有的数据都在ios设备之间共享。它的工作方式类似于NSPersistentContainer，但是它在icloud服务器上发送更改的副本，因此始终存在本地数据缓存。

现在，我想从我的Apple Watch伴侣应用访问该数据，但不是所有数据，而是特定实体！那我该怎么办呢？我试图通过属性检查器设置两个目标之间共享的NSPersistentCloudKitContainer，但注意没有得到任何数据。我可以在cloudKit仪表板中看到watchOS发出的请求，但手表只是没有得到任何数据。

但是如果我将手表中的实体保存到核心数据中，则只能从手表中获取它。我的结论是，两者都没有将数据存储在同一位置。那么我该如何解决呢？已经使用相同的NSPersistendCloudKitContainer。

两个目标之间共享的容器：

import Foundation
import CoreData

public class CoreDataContainer {
    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 = NSPersistentCloudKitContainer(name: "MyProjectName")
        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)")
            }
        }
    }
}

Answer 1

通过在我的上下文描述中添加一个cloudKitContainerOptions来解决：

class CoreDataStack {
    static let persistentContainer: NSPersistentCloudKitContainer = {
        let container = NSPersistentCloudKitContainer(name: "MyProjectName")
        let description = container.persistentStoreDescriptions.first

        description?.cloudKitContainerOptions = NSPersistentCloudKitContainerOptions(containerIdentifier: "myCloudContainerID") // HERE !

        container.loadPersistentStores(completionHandler: { (_, error) in
            if let error = error as NSError? {
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
        return container
    }()  

}