Preload into Core Data

private func preloadData() {
        let preloadedDataKey = "didPreloadData"

        let userDefaults = UserDefaults.standard

        if userDefaults.bool(forKey: preloadedDataKey) == false {

            guard let urlPath = Bundle.main.url(forResource: "Services", withExtension: "plist", subdirectory: "Data") else {
                return
            }

            print(urlPath)

            let backgroundContext = persistentContainer.newBackgroundContext()
            persistentContainer.viewContext.automaticallyMergesChangesFromParent = true

            backgroundContext.perform {
                if let arrayContents = NSArray(contentsOf: urlPath) as? [Service] {

                    do {

                        for item in arrayContents {
                            let serviceObject = Service(context: backgroundContext)
                            serviceObject.name = item.name!
                            serviceObject.slug = item.slug!
                            serviceObject.url = item.url!
                        }

                        try backgroundContext.save()
                        userDefaults.set(true, forKey: preloadedDataKey)
                    } catch {
                        print(error.localizedDescription)
                    }
                }
            }

        }
    }