Swift-用iCloud核心数据替换核心数据

Question

如何用iCloud核心数据替换现有的核心数据？ 这是我的persistentStoreCoordinator：

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
    // The persistent store coordinator for the application. This implementation creates and return 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
    var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)

    var notificacionCenter: NSNotificationCenter = NSNotificationCenter.defaultCenter()
    notificacionCenter.addObserver(self, selector: "storesWillChange:", name:NSPersistentStoreCoordinatorStoresWillChangeNotification, object: coordinator)
    notificacionCenter.addObserver(self, selector: "storesDidChange:", name:NSPersistentStoreCoordinatorStoresDidChangeNotification, object: coordinator)
    notificacionCenter.addObserver(self, selector: "persistentStoreDidImportUbiquitousContentChanges:", name:NSPersistentStoreDidImportUbiquitousContentChangesNotification, object: coordinator)

    let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("MyApp.sqlite")
    var error: NSError? = nil
    var failureReason = "There was an error creating or loading the application's saved data."
    var options: NSDictionary = [NSMigratePersistentStoresAutomaticallyOption : NSNumber(bool: true), NSInferMappingModelAutomaticallyOption : NSNumber(bool: true),
        NSPersistentStoreUbiquitousContentNameKey : "iCloudStore"]
    if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: options, error: &error) == nil {
        coordinator = nil
        // Report any error we got.
        let dict = NSMutableDictionary()
        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
        dict[NSLocalizedFailureReasonErrorKey] = failureReason
        dict[NSUnderlyingErrorKey] = error
        error = 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 \(error), \(error!.userInfo)")
        abort()
    }

    return coordinator
}()

我添加通知，然后呢？ 如何更换呢？

Answer 1

您无需执行任何操作即可将iCloud存储的数据替换为本地存储的数据。 也就是说，本地iCore数据会使用iCloud下载的数据进行更新，并在此之后保持一致，而无需担心。

但是，如果您已经在UI中显示了数据，那么当“新iCloud数据”到达时，“旧本地数据”可能仍会显示。 与iCould一起使用SQLite商店中的Apple文档介绍了如何通过通知处理更新。 总结一下该引用：在NSPersistentStoreCoordinatorStoresWillChangeNotification的处理程序中，如果存在任何未决的更改，则将它们保存，否则将重置托管对象上下文并禁用用户界面。 然后，在NSPersistentStoreCoordinatorStoresDidChangeNotification处理程序中，更新显示的数据（和其他数据）并重新启用UI。

这就是我用于带iCloud的Core Data的功能。 storeOptions是关键。 对于Xcode目标，您需要启用iCloud功能并确保已选择“ iCloud文档”。

{
  // ...

  lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
    // The persistent store coordinator for the application. This implementation
    // creates and return 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
    var coordinator: NSPersistentStoreCoordinator =
      NSPersistentStoreCoordinator (managedObjectModel: self.managedObjectModel)

    var storeURL =
      self.applicationDocumentsDirectory
        .URLByAppendingPathComponent("iAppSwift.sqlite")

    var storeOptions =
      [NSPersistentStoreUbiquitousContentNameKey : "iAppSwiftStore"
      // NSPersistentStoreRebuildFromUbiquitousContentOption: @(true)
        ]

    // 
    self.registerCoordinatorForStoreNotifications (coordinator)

    var error : NSError? = nil
    var store : NSPersistentStore! =
      coordinator.addPersistentStoreWithType (NSSQLiteStoreType,
        configuration: nil,
        URL: storeURL,
        options: storeOptions,
        error: &error)

    if nil == store {
      // handle error
    }

    return coordinator
  }()

  func registerCoordinatorForStoreNotifications (coordinator : NSPersistentStoreCoordinator) {
    let nc : NSNotificationCenter = NSNotificationCenter.defaultCenter();

    nc.addObserver(self, selector: "handleStoresWillChange:",
      name: NSPersistentStoreCoordinatorStoresWillChangeNotification,
      object: coordinator)

    nc.addObserver(self, selector: "handleStoresDidChange:",
      name: NSPersistentStoreCoordinatorStoresDidChangeNotification,
      object: coordinator)

    nc.addObserver(self, selector: "handleStoresWillRemove:",
      name: NSPersistentStoreCoordinatorWillRemoveStoreNotification,
      object: coordinator)

    nc.addObserver(self, selector: "handleStoreChangedUbiquitousContent:",
      name: NSPersistentStoreDidImportUbiquitousContentChangesNotification,
      object: coordinator)
  }

  // ...
}