将现有应用程序从NSPersistentContainer迁移到NSPersistentCloudKitContainer

Question

我有一个只使用本地设备CoreData (NSPersistentContainer)的应用程序。我正在寻找迁移，以便该应用程序与NSPersistentCloudKitContainer兼容。我了解NSPersistentCloudKitContainer的所有CloudKit设置，但如何将播放器手机上的数据迁移到iCloud？(即如何将现有的核心数据从NSPersistentContainer迁移到NSPersistentCloudKitContainer)？

Answer 1

如何做到这一点在2019年WWDC视频“Using Core Data With CloudKit”中给出了一个很好的介绍。

要点是：

• 使用容器函数NSPersistentContainer替换iCloud架构的ist子类(此操作只需在设置或更改核心数据模型后执行一次)。initializeCloudKitSchema
• 在iCloud仪表板中，创建每个自定义类型(这些类型以CD_开头)并将所有经过身份验证的用户的所有CD_记录类型的安全类型设置为read/write.
• Implement
• iCloud CD_

如果您有多个持久存储(例如，一个仅与一台设备相关的本地存储，一个与具有相同Apple ID的所有用户共享的私有存储，以及一个与其他用户共享的共享存储)，一种设置方法如下：

    private (set) lazy var persistentContainer: NSPersistentCloudKitContainer! = {
        // This app uses 3 stores: 
        //  - A local store that is user-specific,
        //  - a private store that is synchronized with the iCloud private database, and
        //  - a shared store that is synchronized with the iCloud shared database.
        
        let persistentStoresLoadedLock = DispatchGroup.init() // Used to wait for loading the persistent stores
    
        // Configure local store
        // --------------------------------------------------------------------------------------------------
        let appDocumentsDirectory = try! FileManager.default.url(for: .documentDirectory, 
                                                                                                                         in: .userDomainMask, 
                                                                                                                         appropriateFor: nil, 
                                                                                                                         create: true)
        let coreDataLocalURL = appDocumentsDirectory.appendingPathComponent("CoreDataLocal.sqlite")
        let localStoreDescription = NSPersistentStoreDescription(url: coreDataLocalURL)
        localStoreDescription.configuration = localConfigurationName
        // --------------------------------------------------------------------------------------------------
    
        // Create a container that can load the private store as well as CloudKit-backed stores.
        let container = NSPersistentCloudKitContainer(name: appName)
        assert(container.persistentStoreDescriptions.count == 1, "###\(#function): Failed to retrieve a persistent store description.")
        let firstPersistentStoreDescription = container.persistentStoreDescriptions.first!
        let storeURL = firstPersistentStoreDescription.url!
        let storeURLwithoutLastPathComponent = storeURL.deletingLastPathComponent
        
        // Configure private store
        // --------------------------------------------------------------------------------------------------
        let privateStoreDescription = firstPersistentStoreDescription
        privateStoreDescription.configuration = privateConfigurationName
        // The options below have to be set before loadPersistentStores
        // Enable history tracking and remote notifications
        privateStoreDescription.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey)
        privateStoreDescription.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey)
        privateStoreDescription.cloudKitContainerOptions!.databaseScope = .private
        // --------------------------------------------------------------------------------------------------
    
        // Configure shared store
        // --------------------------------------------------------------------------------------------------
        let sharedStoreURL = storeURLwithoutLastPathComponent().appendingPathComponent("Shared")
        let sharedStoreDescription = NSPersistentStoreDescription(url: sharedStoreURL)
        sharedStoreDescription.configuration = sharedConfigurationName
        sharedStoreDescription.timeout                                                          = firstPersistentStoreDescription.timeout
        sharedStoreDescription.type                                                                 = firstPersistentStoreDescription.type
        sharedStoreDescription.isReadOnly                                                   = firstPersistentStoreDescription.isReadOnly
        sharedStoreDescription.shouldAddStoreAsynchronously                 = firstPersistentStoreDescription.shouldAddStoreAsynchronously
        sharedStoreDescription.shouldInferMappingModelAutomatically = firstPersistentStoreDescription.shouldInferMappingModelAutomatically
        sharedStoreDescription.shouldMigrateStoreAutomatically          = firstPersistentStoreDescription.shouldMigrateStoreAutomatically
        // The options below have to be set before loadPersistentStores
        // Enable history tracking and remote notifications
        sharedStoreDescription.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey)
        sharedStoreDescription.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey)
        sharedStoreDescription.cloudKitContainerOptions = NSPersistentCloudKitContainerOptions.init(containerIdentifier: "iCloud.com.zeh4soft.shop")
        // For sharing see https://developer.apple.com/documentation/cloudkit/shared_records
        // and https://medium.com/@adammillers/cksharing-step-by-step-33800c8950d2
        sharedStoreDescription.cloudKitContainerOptions!.databaseScope = .shared
        // --------------------------------------------------------------------------------------------------
    
        container.persistentStoreDescriptions = [localStoreDescription, privateStoreDescription, sharedStoreDescription]
        for _ in 1 ... container.persistentStoreDescriptions.count { persistentStoresLoadedLock.enter() }
    
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            // The completion handler will be called once for each persistent store that is created.
            guard error == nil else {
                /*
                Apple suggests to replace this implementation with code to handle the error appropriately.
                However, there is not really an option to handle it, see <https://stackoverflow.com/a/45801384/1987726>.
                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("###\(#function): Failed to load persistent stores: \(error!)")
            }
            if storeDescription.configuration == self.privateConfigurationName {
                /*
                Only if the schema has been changed, it has to be re-initialized.
                Due to an Apple bug, this can currently (iOS 13) only be done with a .private database!
                A re-initialization requires to run the app once using the scheme with the "-initSchema" argument.
                After schema init, ensure in the Dashboard:
                For every custom type, recordID and modTime must have queryable indexes.
                All CD record types must have read/write security type for authenticated users.
                Run later always a scheme without the "-initSchema" argument.
                */
                if ProcessInfo.processInfo.arguments.contains("-initSchema") {
                    do {
                        try container.initializeCloudKitSchema(options: .printSchema)
                    } catch {
                        print("-------------------- Could not initialize cloud kit schema --------------------")
                    }
                }
            }
            persistentStoresLoadedLock.leave() // Called for all stores
        })
        let waitResult = persistentStoresLoadedLock.wait(timeout: .now() + 100) // Wait for local, private and shared stores loaded
        if waitResult != .success { fatalError("Timeout while loading persistent stores") }
        return container
    }   ()  

编辑：

privateConfigurationName和sharedConfigurationName都是Strings

let privateConfigurationName = "Private"
let sharedConfigurationName  = "Shared"  

Private和Shared作为核心数据模型中的配置名称，例如：

​

​

必须在那里将实体分配给持久存储。

警告：

如果您将同一实体分配给多个持久性存储区，则托管上下文的保存会将其存储在所有分配的存储区中，除非您指定了特定的存储区，请参阅this post。

同样，fetch将从实体分配到的所有持久存储中获取一条记录，除非在fetch请求中设置了affectedStores，请参阅the docs。

Answer 2

我做了以下工作：

添加了支持NSPersistentCloudKitContainer

• And的history tracking

的

• 取代了NSPersistentContainer

container = NSPersistentCloudKitContainer(name: "myApp") // <<<<< this
if inMemory {
    container.persistentStoreDescriptions.first!.url = URL(fileURLWithPath: "/dev/null")
}
        
let description = container.persistentStoreDescriptions.first
description?.setOption(true as NSNumber, 
                       forKey: NSPersistentHistoryTrackingKey) // <<<<< this

container.viewContext.automaticallyMergesChangesFromParent = true
container.loadPersistentStores(...)

编辑：嗯，我说得太快了。它不工作:(

我发现人们在这里https://developer.apple.com/forums/thread/120328有一些小技巧(例如，编辑项目以触发同步，或者像这里解释的那样手动传输每个对象https://medium.com/@dmitrydeplov/coredata-cloudkit-integration-for-a-live-app-57b6cfda84ad)

但是没有实际的答案。