Core Data: preloading an existing SQLite database

AppDelegate.swift

import UIKit
import CoreData

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        return true
    }

    lazy var applicationDocumentsDirectory: NSURL = {
        let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
        return urls[urls.count-1]
    }()

    lazy var managedObjectModel: NSManagedObjectModel = {
        let modelURL = NSBundle.mainBundle().URLForResource("Database", withExtension: "momd")!
        return NSManagedObjectModel(contentsOfURL: modelURL)!
    }()

    lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
        let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
        let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("Database.sqlite")
        
        if !NSFileManager.defaultManager().fileExistsAtPath(url.path!) {
            let sourceURL = NSBundle.mainBundle().URLForResource("Database", withExtension: "sqlite")!

            do {
                try NSFileManager.defaultManager().copyItemAtURL(sourceURL, toURL: url)
            } catch let error as NSError {
                print("Unresolved error: \(error.userInfo)")
            }
        }
        
        do {
            try coordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil)
        } catch let error as NSError {
            print("Unresolved error: \(error.userInfo)")
        }
        
        return coordinator
    }()

    lazy var managedObjectContext: NSManagedObjectContext = {
        let coordinator = self.persistentStoreCoordinator
        var managedObjectContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)
        managedObjectContext.persistentStoreCoordinator = coordinator
        return managedObjectContext
    }()

    func saveContext() {
        if managedObjectContext.hasChanges {
            do {
                try managedObjectContext.save()
            } catch let error as NSError {
                print("Unresolved error: \(error.userInfo)")
            }
        }
    }
}

https://gist.github.com/xavierchia/ef43abb270003ae63e5bbb7eb5404645

For the latest XCode and Swift