title: Swift 3 preload from SQL files in appDelegate
body: <p>I am attempting a swift 3 conversion. I was preloading data from sql files in my swift 2 project. I am unsure how to make this work in swift 3.0? Below is my swift 2 appDelegate file. In swift 3 the core data stack has changed enough, that I do not know where to try to reuse the same code that worked for me with swift 2. The code i was using that worked is listed under the comment "added for SQLite preload". Thank you</p>
  
  <pre><code>    // MARK: - Core Data stack
  
  lazy var applicationDocumentsDirectory: URL = {
      // The directory the application uses to store the Core Data store file. This code uses a directory named "self.edu.SomeJunk" in the application's documents Application Support directory.
      let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
      return urls[urls.count-1]
  }()
  
  lazy var managedObjectModel: NSManagedObjectModel = {
      // The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
      let modelURL = Bundle.main.url(forResource: "ESLdata", withExtension: "momd")!
      return NSManagedObjectModel(contentsOf: modelURL)!
  }()
  
  lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
      // The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
      // Create the coordinator and store
      let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
  
      let url = self.applicationDocumentsDirectory.appendingPathComponent("ESLdata.sqlite")
  
  
  
      //ADDED FOR SQLITE PRELOAD
      // Load the existing database
      if !FileManager.default.fileExists(atPath: url.path) {
          let sourceSqliteURLs = [Bundle.main.url(forResource: "ESLdata", withExtension: "sqlite")!,Bundle.main.url(forResource: "ESLdata", withExtension: "sqlite-wal")!, Bundle.main.url(forResource: "ESLdata", withExtension: "sqlite-shm")!]
          let destSqliteURLs = [self.applicationDocumentsDirectory.appendingPathComponent("ESLdata.sqlite"), self.applicationDocumentsDirectory.appendingPathComponent("ESLdata.sqlite-wal"), self.applicationDocumentsDirectory.appendingPathComponent("ESLdata.sqlite-shm")]
          for index in 0 ..&lt; sourceSqliteURLs.count {
              do {
                  try FileManager.default.copyItem(at: sourceSqliteURLs[index], to: destSqliteURLs[index])
              } catch {
                  print(error)
              }
          }
      }
      // END OF ADDED CODE
  
  
  
      var failureReason = "There was an error creating or loading the application's saved data."
      do {
          try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options:  [NSMigratePersistentStoresAutomaticallyOption:true, NSInferMappingModelAutomaticallyOption:true])
      } catch {
          // Report any error we got.
          var dict = [String: AnyObject]()
          dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject?
          dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject?
  
          dict[NSUnderlyingErrorKey] = error as NSError
          let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
          // Replace this with code to handle the error appropriately.
          // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
          NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
          abort()
      }
  
      return coordinator
  }()
  
  lazy var managedObjectContext: NSManagedObjectContext = {
      // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
      let coordinator = self.persistentStoreCoordinator
      var managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
      managedObjectContext.persistentStoreCoordinator = coordinator
      return managedObjectContext
  }()
  
  // MARK: - Core Data Saving support
  
  func saveContext () {
      if managedObjectContext.hasChanges {
          do {
              try managedObjectContext.save()
              print("SAVED")
          } catch {
              print("Save Failed")
  
              let nserror = error as NSError
              NSLog("Unresolved error \(nserror), \(nserror.userInfo)")
              abort()
          }
      }
  }
  </code></pre>
  
  <p>The following is what I attempted to update the code to, and had no luck:</p>
  
  <pre><code>func getDocumentsDirectory()-&gt; URL {
      let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
      let documentsDirectory = paths[0]
      return documentsDirectory
  }
  
  // MARK: - Core Data stack
  
  lazy var persistentContainer: NSPersistentContainer = {
      /*
       The persistent container for the application. This implementation
       creates and returns a container, having loaded the store for the
       application to it. This property is optional since there are legitimate
       error conditions that could cause the creation of the store to fail.
       */
  
  
  
  
  
      let container = NSPersistentContainer(name: "ESLdata")
      container.loadPersistentStores(completionHandler: { (storeDescription, error) in
          if let error = error as NSError? {
              // Replace this implementation with code to handle the error appropriately.
              // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
  
              /*
               Typical reasons for an error here include:
               * The parent directory does not exist, cannot be created, or disallows writing.
               * The persistent store is not accessible, due to permissions or data protection when the device is locked.
               * The device is out of space.
               * The store could not be migrated to the current model version.
               Check the error message to determine what the actual problem was.
               */
              fatalError("Unresolved error \(error), \(error.userInfo)")
          }
          //ADDED FOR SQLITE PRELOAD
  
          let url = self.getDocumentsDirectory().appendingPathComponent("ESLdata.sqlite")
          // Load the existing database
  
          if !FileManager.default.fileExists(atPath: url.path) {
              let sourceSqliteURLs = [Bundle.main.url(forResource: "ESLdata", withExtension: "sqlite")!,Bundle.main.url(forResource: "ESLdata", withExtension: "sqlite-wal")!, Bundle.main.url(forResource: "ESLdata", withExtension: "sqlite-shm")!]
              let destSqliteURLs = [self.getDocumentsDirectory().appendingPathComponent("ESLdata.sqlite"), self.getDocumentsDirectory().appendingPathComponent("ESLdata.sqlite-wal"), self.getDocumentsDirectory().appendingPathComponent("ESLdata.sqlite-shm")]
              for index in 0 ..&lt; sourceSqliteURLs.count {
                  do {
                      try FileManager.default.copyItem(at: sourceSqliteURLs[index], to: destSqliteURLs[index])
                  } catch {
                      print(error)
                  }
              }
          }
          // END OF ADDED CODE
  
  
      })
      return container
  }()
  
  // MARK: - Core Data Saving support
  
  func saveContext () {
      let context = persistentContainer.viewContext
      if context.hasChanges {
          do {
              try context.save()
          } catch {
              // Replace this implementation with code to handle the error appropriately.
              // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
              let nserror = error as NSError
              fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
          }
      }
  }
  </code></pre>