Core data + CloudKit - sharing between iOS and watchOS companion app - core-data

Question

In my app I store data with core data.
Recently I discovered the new feature introduced by Apple in WWDC19 which allows core data to work with CloudKit.
I just enabled cloudKit for my app and used an NSPersistentCloudKitContainer instead of NSPersistentContainer and all was set up ! All my data is shared between ios devices.
That works like NSPersistentContainer but it sends a copy of changes on icloud server, so there is always a local cache of data.
Now I'd like to access that data from my apple watch companion app but not all the data, only a specific entity!
So how could I do that?
I tried to set the NSPersistentCloudKitContainer shared between both targets with the attribut inspector but watch don't get any data. I can see in cloudKit dashboard there are requests from watchOS but watch just don't get any data.
But if I save an entity from the watch to core data I can get it only from the watch.
My conclusion is both are no storing the data at the same place. So how could I fix that? There are already using the same NSPersistendCloudKitContainer.
the container shared between both targets :
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

Resolved by adding a cloudKitContainerOptions to my context description like this :
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
}()
}