iOS 18下SwiftData删除播放列表触发致命错误求助

问题详情 #

适配iOS 18时，使用SwiftData内存存储数据，删除播放列表时触发致命错误：

Thread 10: Fatal error: Never access a full future backing data - PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(url: x-coredata://4885953A-BDB2-4CD1-9299-B2FBBB899EB7/PlaylistItem/p372), implementation: SwiftData.PersistentIdentifierImplementation) with Optional(B2A80504-2FE1-4C86-8341-3DDE8B6AB913)

触发错误的代码：

func deletePlaylist(_ playlist: PlayListModel) async throws {
        print("attempt to delate :, \(playlist.playlistName)")
        context.delete(playlist)
        try context.save() // error here on the save 
    }

该问题仅在iOS 18中出现，iOS 17下无异常。

可行解决方案 #

• 确保上下文线程安全：SwiftData的ModelContext不支持跨线程操作，将删除逻辑放到上下文的执行队列中：

  func deletePlaylist(_ playlist: PlayListModel) async throws {
      try await context.perform {
          print("attempt to delete :, \(playlist.playlistName)")
          self.context.delete(playlist)
          try self.context.save()
      }
  }
  

• 验证对象的上下文关联性：iOS 18对对象所属上下文的检查更严格，先确认对象是否在当前上下文内，若不在则重新获取：

  func deletePlaylist(_ playlist: PlayListModel) async throws {
      guard context.registeredObjects.contains(playlist) else {
          let fetchDescriptor = FetchDescriptor<PlayListModel>(predicate: #Predicate { $0.id == playlist.id })
          guard let validPlaylist = try context.fetch(fetchDescriptor).first else { return }
          context.delete(validPlaylist)
          try context.save()
          return
      }
      context.delete(playlist)
      try context.save()
  }
  

• 检查内存存储配置：确认初始化ModelContainer时明确设置内存存储，避免iOS 18下的默认配置变化：

  let container = try ModelContainer(
      for: PlayListModel.self,
      configurations: ModelConfiguration(isStoredInMemoryOnly: true)
  )
  

• 调整保存时机：尝试延迟保存操作，给SwiftData足够的时间处理对象状态：

  func deletePlaylist(_ playlist: PlayListModel) async throws {
      context.delete(playlist)
      try await Task.sleep(nanoseconds: 100_000_000)
      try context.save()
  }
  

内容的提问来源于stack exchange，提问作者Damiano Miazzi