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")
        }
    }
}

Go here and click [download container], from the file go to Show Package Contents > App Data > Library > Application Support

Make sure you add the files to your folder and app bundle at Targets > Build Phases > Copy Bundle Resources. I personally like to put the source files in Model folder > Preload data folder

Don't forget to check Target Membership

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.