Knowing when the watch app receives a push notification from Cloudkit

Question

I have an app that has an Apple Watch extension.

Both use Core Data.

I have enabled, on both, the CloudKit ability.

I have configured both apps as described here

I open the iOS app, change the database, but nothing happens on the watch. I mean, the results are not updated on the watch.

Two questions:

1. Do I have to do something to push or to receive the notification from iCloud?
2. How do I know when the watch receives some notification from iCloud? Is that a way to debug this?

Answer 1

I have configured both my iOS and Watch apps following 100% of what Apple wrote on the document I mention on the question, and the apps were not synching over CloudKit.

The solution was to modify PersistenceController to this:

import CoreData

struct PersistenceController {
  static let shared = PersistenceController()
  let container: NSPersistentCloudKitContainer
  
  var context: NSManagedObjectContext {
    return container.viewContext
  }
  
  init(inMemory: Bool = false) {
    container = NSPersistentCloudKitContainer(name: "MyApp")
    container.viewContext.automaticallyMergesChangesFromParent = true
    container.viewContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy

    guard let description = container.persistentStoreDescriptions.first else{
      fatalError("###\(#function): Failed to retrieve a persistent store description.")
    }
    
    description.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey)
    
    // Generate NOTIFICATIONS on remote changes
    description.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey)
    description.cloudKitContainerOptions = NSPersistentCloudKitContainerOptions(containerIdentifier: "iCloud.com.myCompany.MyApp")

    
    if inMemory {
      container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
    }

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

Then remove the apps from your iPhone and Watch and run again. It will work instantly.