Włączenie podstawowe dane lekki migracja Swift 3

Question

Według artykułów czytałem poprawny sposób, aby umożliwić podstawowych migracje lekka waga danych jest przekazując opcje addPersistentStoreWithType:

let mOptions = [NSMigratePersistentStoresAutomaticallyOption: true, 
NSInferMappingModelAutomaticallyOption: true] 

try coordinator!.addPersistentStoreWithType(
NSSQLiteStoreType, configuration: nil, URL: url, options: mOptions) 

Ale w moim projekcie Xcode 8Swift 3 mogę nie wiadomo, gdzie jest wywoływane addPersistentStoreWithType. To jest tylko kod core data który został wygenerowany, gdy tworzę projekt:

// 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: "Habits") 
    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)") 
     } 
    }) 
    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)") 
     } 
    } 
} 

Jak włączyć lekkie migracje w Xcode 8 Korzystanie Swift 3?

Answer 1

to zrobić za pomocą NSPersistentStoreDescription, czyli tam, gdzie wszystkie te opcje przeniósł się w Swift 3 aktualizacje. Zrób to przed wywołaniem loadPersistentStores:

let description = NSPersistentStoreDescription() 

description.shouldInferMappingModelAutomatically = true 
description.shouldMigrateStoreAutomatically = true 

container.persistentStoreDescriptions = [description] 

Answer 2

Możesz po prostu rozpocząć nowy projekt w Xcode 7, a następnie skopiować i wkleić wygenerowany główny kod danych do nowego nowego projektu!

Utworzono projekt w Xcode 7 i zmigrowałem go do Xcode 8, jest to wygenerowany kod. (Mam już dodane dwie opcje umożliwiające migrację lekki stosu)

// 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 "com.MyApp" 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: "MyApp", 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("SingleViewCoreData.sqlite") 
    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() 
     } catch { 
      // Replace this implementation 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. 
      let nserror = error as NSError 
      NSLog("Unresolved error \(nserror), \(nserror.userInfo)") 
      abort() 
     } 
    } 
} 

można po prostu skopiować i wkleić powyższy go w App Delegata.

Jedną rzeczą, aby pamiętać, że należy zmodyfikować ten wiersz tak, że dostaje adres URL model danych jest:

let modelURL = Bundle.main.url(forResource: "MyApp", withExtension: "momd")! 

Answer 3

Należy zauważyć, że zarówno NSPersistentStore „s shouldInferMappingModelAutomatically i shouldMigrateStoreAutomatically są true domyślnie.

Jabłko referencyjna:

• shouldInferMappingModelAutomatically

• shouldMigrateStoreAutomatically

Answer 4

W moim przypadku dokonania dołączyć do nowego opisu zamiast wymiany

let description = NSPersistentStoreDescription() 
description.shouldInferMappingModelAutomatically = true 
description.shouldMigrateStoreAutomatically = true 
container.persistentStoreDescriptions.append(description)