NSPersistentCloudKitContainer公共数据库完全不同步问题求助

私有数据库的Item数据可在设备间正常同步，但公共数据库的PublicItem完全无法同步。相关实现代码及配置如下：

相关代码 #

1. 私有数据获取视图代码 #

@Environment(\.managedObjectContext) private var viewContext
@FetchRequest(
    sortDescriptors: [NSSortDescriptor(keyPath: \Item.timestamp, ascending: false)],
    animation: .default)
private var items: FetchedResults<Item>

2. 公共数据获取视图代码 #

@Environment(\.managedObjectContext) var viewContext
@FetchRequest(
    sortDescriptors: [NSSortDescriptor(keyPath: \PublicItem.timestamp, ascending: false)],
    animation: .default)
private var publicItems: FetchedResults<PublicItem>

3. Persistence.swift代码 #

import CoreData
import CloudKit

struct PersistenceController {
    static let shared = PersistenceController()

    static var preview: PersistenceController = {
        let result = PersistenceController(inMemory: true)
        let viewContext = result.container.viewContext
        for _ in 0..<2 {
            let newItem = Item(context: viewContext)
            newItem.timestamp = Date()
            newItem.name = "Test-Item"
        }

        do {
            try viewContext.save()
        } catch {
            let nsError = error as NSError
            fatalError("Unresolved error \(nsError), \(nsError.userInfo)")
        }
        return result
    }()

    let container: NSPersistentCloudKitContainer

    init(inMemory: Bool = false) {
        container = NSPersistentCloudKitContainer(name: "ear2brain")
            
        let privateStoreDescription = NSPersistentStoreDescription(url: FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("private.sqlite"))
        privateStoreDescription.configuration = "private"
        privateStoreDescription.cloudKitContainerOptions = NSPersistentCloudKitContainerOptions(containerIdentifier: "iCloud.ear2brain")
        privateStoreDescription.cloudKitContainerOptions?.databaseScope = .private

        let publicStoreDescription = NSPersistentStoreDescription(url: FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("public.sqlite"))
        publicStoreDescription.configuration = "public"
        publicStoreDescription.cloudKitContainerOptions = NSPersistentCloudKitContainerOptions(containerIdentifier: "iCloud.ear2brain")
        publicStoreDescription.setOption(true as NSNumber, forKey: NSPersistentHistoryTrackingKey)
        publicStoreDescription.setOption(true as NSNumber, forKey: NSPersistentStoreRemoteChangeNotificationPostOptionKey)
        publicStoreDescription.cloudKitContainerOptions?.databaseScope = .public

        container.persistentStoreDescriptions = [privateStoreDescription, publicStoreDescription]

        if inMemory {
            container.persistentStoreDescriptions.first?.url = URL(fileURLWithPath: "/dev/null")
            container.persistentStoreDescriptions.last?.url = URL(fileURLWithPath: "/dev/null")
        }

        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })

        container.viewContext.automaticallyMergesChangesFromParent = true
        container.viewContext.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy

        do {
            try container.viewContext.setQueryGenerationFrom(.current)
        } catch {
            fatalError("Failed to pin viewContext to the current generation:\(error)")
        }
    }
}

配置说明 #

PublicItem和Item属性一致，分别对应public和private配置，所有配置（public、default、private）均已勾选CloudKit使用。

排查与解决方案 #

• 检查CloudKit容器公共数据库权限
  登录CloudKit控制台，确认对应容器的公共数据库中，PublicItem对应的记录类型权限设置为允许读写，且当前测试设备的Apple ID具备访问权限。公共数据库默认权限为Users can read/write，若权限被修改为更严格的规则，会直接导致同步失败。

• 验证PublicItem的Core Data实体配置
  打开xcdatamodeld文件，确认PublicItem实体的Configuration选择为public，且CloudKit Integration选项已勾选，同时所有属性的CloudKit字段映射正确（比如timestamp映射为日期类型，name映射为字符串类型）。

• 修正视图上下文与公共存储的关联
  默认的container.viewContext绑定的是第一个持久化存储（即私有存储），操作PublicItem时需使用关联公共存储的上下文。可以通过以下方式创建并使用专属上下文：

  // 创建公共存储专属上下文
  func publicContext() -> NSManagedObjectContext {
      let context = container.newBackgroundContext()
      guard let publicStoreURL = container.persistentStoreDescriptions.first(where: { $0.configuration == "public" })?.url,
            let publicStore = container.persistentStoreCoordinator.persistentStore(for: publicStoreURL) else {
          fatalError("Failed to get public persistent store")
      }
      context.persistentStoreCoordinator = container.persistentStoreCoordinator
      try? context.setPersistentStore(publicStore)
      context.automaticallyMergesChangesFromParent = true
      context.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy
      return context
  }
  

  在创建或查询PublicItem时，使用该publicContext()替代默认的viewContext，确保操作被正确路由到公共存储并同步到CloudKit。

• 查看同步错误日志
  在Xcode中打开Window > Devices and Simulators，选择测试设备后点击View Device Logs，搜索CoreDataCloudKit关键字，日志中会包含同步失败的具体原因（如权限问题、实体映射错误、网络异常等），这是定位问题的关键依据。

• 确认测试环境一致性
  确保所有测试设备使用同一个Apple ID登录并开启iCloud同步，且App的iCloud容器标识符统一为iCloud.ear2brain，避免因容器不一致导致同步失效。

内容的提问来源于stack exchange，提问作者someone