核心数据+CloudKit-iOS和watchOS配套应用程序之间的共享

Question

在我的应用程序中，我将数据与核心数据一起存储。最近，我发现了苹果在WWDC19中引入的新功能，它允许核心数据与CloudKit一起工作。我刚刚为我的应用程序启用了cloudKit，并使用了NSPersistentCloudKitContainer而不是NSPersistennContainer，一切都设置好了！我的所有数据都在ios设备之间共享。这与NSPersistentContainer类似，但它在icloud服务器上发送更改的副本，因此总是有一个本地数据缓存。

现在我想从我的apple watch配套应用程序中访问这些数据，但不是所有的数据，只是一个特定的实体！那我该怎么做呢？我试图用attribut检查器设置两个目标之间共享的NSPersistentCloudKitContainer，但观察没有得到任何数据。我可以在cloudKit仪表板中看到来自watchOS的请求，但watch没有得到任何数据。

但如果我将一个实体从手表保存到核心数据，我只能从手表中获得它。我的结论是，两者都不能将数据存储在同一个地方。那我该怎么解决呢？已在使用相同的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cloudKitContainerOptions来解决，如下所示：

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
}()  
}