Preload Sqlite data to Core Data

# In AppDelegate:


# This is to make sure that it only happens on the first launch

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    let defaults = UserDefaults.standard
    let isPreloaded = defaults.bool(forKey: "isPreloaded")
    if !isPreloaded {
        print("Preloading data for the first time")
        preloadData()
        defaults.set(true, forKey: "isPreloaded")
    }
    return true
}
    
    
# Preload the data   

func preloadData() {
let sourceSqliteURLs = [Bundle.main.url(forResource: "DataModel", withExtension: "sqlite"), Bundle.main.url(forResource: "DataModel", withExtension: "sqlite-wal"), Bundle.main.url(forResource: "DataModel", withExtension: "sqlite-shm")]

    let destSqliteURLs = [
        URL(fileURLWithPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/DataModel.sqlite"),
        URL(fileURLWithPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/DataModel.sqlite-wal"),
        URL(fileURLWithPath: NSPersistentContainer.defaultDirectoryURL().relativePath + "/DataModel.sqlite-shm")]

    for index in 0...sourceSqliteURLs.count-1 {
        do {
            try FileManager.default.copyItem(at: sourceSqliteURLs[index]!, to: destSqliteURLs[index])
        } catch {
            print("Could not preload data")
        }
    }
}

With SwiftUIApp, the process seems to be quite straightforward as well. The following approach seems to work for me.
If you are using the XCode-generated persistance model you have to replace this line

    let persistence = PersistenceManager()

in your main app fille with this

    let persistence: PersistenceManager
    
    init() {
        let defaults = UserDefaults.standard
        let isPreloaded = defaults.bool(forKey: "isPreloaded")
        if !isPreloaded {
            print("Preloading data for the first time")
// copy the contents of preloadData function here
            defaults.set(true, forKey: "isPreloaded")
        }
        persistence = PersistenceManager()
    }

This is fantastic thank you!!!!!!! I've searched for hours for a solution.