Json Batch insertion: Corrected sample from WWDC19 needed

Give something like this a try:

func syncLocations() {
        var batchCreate: [[String: Any]] = []
        for location in remoteLocations {
            if let objectID = locationDataSource.performFetchObjectID(Location.requestLocationStruct(location)) {
                let updateObj = locationDataSource.updateContext.object(with: objectID) as! Location
                let (latitude, longitude) = invalidCoordinates(updateObj.provider, updateObj.slug)
                updateObj.latitude = latitude
                updateObj.longitude = longitude
                locationDataSource.saveUpdateObject()
            } else {
                let (latitude, longitude) = invalidCoordinates(location.provider, location.slug!)
                batchCreate.append(
                    [
                        "uniqueID": UUID().uuidString,
                        "title": location.title,
                        "name": location.name ?? "",
                        "slug": location.slug ?? "",
                        "subtitle": location.subtitle ?? "",
                        "locale": location.locale ?? "",
                        "provider": location.provider,
                        "latitude": latitude,
                        "longitude": longitude
                    ])
                }
        }
        let request = NSBatchInsertRequest(entityName: Location.entityName, objects: batchCreate)
        locationDataSource.performBatchInsert(request, "location")
    }

...

    func performBatchInsert(_ request: NSBatchInsertRequest, _ author: String = appTransactionAuthorName) {
        do {
            createContext.transactionAuthor = author
            try createContext.executeAndMergeChanges(using: request)
        } catch {
            print(error)
        }
    }

extension NSManagedObjectContext {
    public func executeAndMergeChanges(using batchInsertRequest: NSBatchInsertRequest) throws {
        batchInsertRequest.resultType = .objectIDs
        let result = try execute(batchInsertRequest) as! NSBatchInsertResult
        let changes: [AnyHashable: Any] = [NSInsertedObjectsKey: result.result as? [NSManagedObjectID] ?? []]
        NSManagedObjectContext.mergeChanges(fromRemoteContextSave: changes, into: [self])
    }
}

The batch insert request basically wants an array of objects that are themselves an array of property key-values. As such, you'll need to make sure the JSON decodes to [[String: Any]]

I got it to work.

There are some spelling mistakes on the presentation.

The objects you pass in need to have the type [[String : Any]]

So you basically have have key value pairs in a list. The strings must match the attribute names in your core data model.

Also you need to cast the insertResult to NSBatchInsertResult. Not NSBatchInsertRequest.

I used an example entity CDTest with the attributes "id" of type Int32 and "name" of type string. I made "id" the constraint.

The following code worked for me then:

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        self.batchInsertExamples()
    }

    func batchInsertExamples() {
        
        var objectsToInsert: [[String : Any]] = []
        for i in 0...5 {
            objectsToInsert.append(["id" : i, "name" : "My Name"])
        }
        
        self.persistentContainer.viewContext.performAndWait {
            do {
                let insertRequest = NSBatchInsertRequest(entity: CDTest.entity(), objects: objectsToInsert)
                let insertResult = try self.persistentContainer.viewContext.execute(insertRequest) as! NSBatchInsertResult
                
                let success = insertResult.result as! Bool
                if !success {
                    print("batch insert was not successful")
                }
            } catch {
                print(error.localizedDescription)
            }
            
            if self.persistentContainer.viewContext.hasChanges {
                do {
                    try self.persistentContainer.viewContext.save()
                } catch {
                    print("Error: \(error)\nCould not save Core Data context.")
                    return
                }
            }
        }
    }

    lazy var persistentContainer: NSPersistentContainer = {
        let container = NSPersistentContainer(name: "nsbatchinsert")
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
            
            container.viewContext.automaticallyMergesChangesFromParent = true
            container.viewContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy
            container.viewContext.undoManager = nil
            container.viewContext.shouldDeleteInaccessibleFaults = true
            
        })
        return container
    }()

}