[英]Migrate local Core Data Store to iCloud for existing project with Swift
我想为现有项目启用 iCloud for Core Data。 用户可以使用新 iPhone 或其他 iPhone 上的应用程序使用他的旧数据。 因此,我必须将可能现有的商店迁移到 iCloud/无处不在的容器中的新商店。
当您使用 iOS 8 创建新的 Swift 项目时,我添加了 iCloud 文档功能并使用 Apple 的默认核心数据堆栈模板。
苹果核心数据栈模板:
lazy var applicationDocumentsDirectory: NSURL = {
let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
return urls[urls.count-1] as! NSURL
}()
lazy var managedObjectModel: NSManagedObjectModel = {
let modelURL = NSBundle.mainBundle().URLForResource("testapp", withExtension: "momd")!
return NSManagedObjectModel(contentsOfURL: modelURL)!
}()
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("testapp.sqlite")
var error: NSError? = nil
var failureReason = "There was an error creating or loading the application's saved data."
if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil, 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 as [NSObject : AnyObject])
NSLog("Unresolved error \(error), \(error!.userInfo)")
abort()
}
return coordinator
}()
lazy var managedObjectContext: NSManagedObjectContext? = {
let coordinator = self.persistentStoreCoordinator
if coordinator == nil {
return nil
}
var managedObjectContext = NSManagedObjectContext()
managedObjectContext.persistentStoreCoordinator = coordinator
return managedObjectContext
}()
// MARK: - Core Data Saving support
func saveContext () {
if let moc = self.managedObjectContext {
var error: NSError? = nil
if moc.hasChanges && !moc.save(&error) {
NSLog("Unresolved error \(error), \(error!.userInfo)")
abort()
}
}
}
我在苹果开发人员处阅读了有关 migratePersistentStore 函数的内容,并在 StackOverflow 上阅读了有关将本地核心数据移动到 iCloud的答案,但我不知道如何在该模板中正确实现这一点。
根据我的理解,我认为,如果 url 指向现有的存储/文件,我必须检查协调器的惰性 var 定义。 如果是这样,我必须使用函数 migratePersistentStore:xmlStore 和选项 NSPersistentStoreUbiquitousContentNameKey 迁移到新商店。
所以我写了一个新的持久化协调器:
具有迁移功能的持久性协调器
lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
// create new iCloud-ready-store
let iCloudStoreUrl = self.applicationDocumentsDirectory.URLByAppendingPathComponent("TestAppiCloud.sqlite")
var iCloudOptions: [NSObject : AnyObject]? = [
NSPersistentStoreFileProtectionKey: NSFileProtectionComplete,
NSMigratePersistentStoresAutomaticallyOption: true,
NSInferMappingModelAutomaticallyOption: true,
NSPersistentStoreUbiquitousContentNameKey: "TestAppiCloudStore"
]
var error: NSError? = nil
var failureReason = "There was an error creating or loading the application's saved data."
if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: iCloudStoreUrl, options: iCloudOptions, error: &error) == nil {
coordinator = nil
// Report any error we got.
var dict = [String: AnyObject]()
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)
NSLog("Unresolved error \(error), \(error!.userInfo)")
abort()
}
// Possible old store migration
let existingStoreUrl = self.applicationDocumentsDirectory.URLByAppendingPathComponent("testapp.sqlite")
let existingStorePath = existingStoreUrl.path
// check if old store exists, then ...
if NSFileManager.defaultManager().fileExistsAtPath(existingStorePath!) {
// ... migrate
var existingStoreOptions = [NSReadOnlyPersistentStoreOption: true]
var migrationError: NSError? = nil
var existingStore = coordinator!.persistentStoreForURL(existingStoreUrl)
coordinator!.migratePersistentStore(existingStore!, toURL: iCloudStoreUrl, options: existingStoreOptions, withType: NSSQLiteStoreType, error: &migrationError)
}
// iCloud Notifications
let notificationCenter = NSNotificationCenter.defaultCenter()
notificationCenter.addObserver(self,
selector: "storeWillChange",
name: NSPersistentStoreCoordinatorStoresWillChangeNotification,
object: coordinator!)
notificationCenter.addObserver(self,
selector: "storeDidChange",
name: NSPersistentStoreCoordinatorStoresDidChangeNotification,
object: coordinator!)
notificationCenter.addObserver(self,
selector: "storeDidImportUbiquitousContentChanges",
name: NSPersistentStoreDidImportUbiquitousContentChangesNotification,
object: coordinator!)
return coordinator
}()
但是当迁移从 coordinator!.migratePersistentStore 开始时,我遇到了一个异常:
var existingStore = coordinator!.persistentStoreForURL(existingStoreUrl) // nil
但文件管理器说,它存在!
我究竟做错了什么? 这个想法正确吗? 请帮忙。
我遇到了与“persistentStoreForURL”完全相同的问题。 事实证明,我一直在寻找类似“persistenStoreWITHUrl”的东西。 我错误地认为它实际上会加载商店,但事实证明,它不会。 当商店已经加载到协调器中时,此功能起作用。 我知道你刚才问过这个问题,但我会把这个留在这里,以防其他人遇到同样的问题。 因此更改代码将使其按预期工作:
let coordinator = self.persistentStoreCoordinator
let existingStore = coordinator.persistentStores.first
var options = Dictionary<NSObject, AnyObject>()
options[NSPersistentStoreRemoveUbiquitousMetadataOption] = true
options[NSMigratePersistentStoresAutomaticallyOption] = true
options[NSInferMappingModelAutomaticallyOption] = true
do {
try coordinator?.migratePersistentStore(existingStore!, to: url2, options: [NSMigratePersistentStoresAutomaticallyOption:true, NSInferMappingModelAutomaticallyOption:true], withType: NSSQLiteStoreType)
}
catch {
print(error)
}
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