Question

我正在viewDidLoad中获取一些项（NSManagedObject），并且我正在使用NSFetchedResultsController委托来更新swift ios中的tableView单元（来自Apple文档的代表进行插入，删除等操作），问题是当我将一个项目添加到相同ManagedObject类型的核心数据中，我希望该表使用新项目进行更新，但是相反，最后一个项目已从tableview中删除，并且不添加新项目。当我再次加载屏幕时，我只会看到新项目……可能是什么问题？这是我的fetchedResultsController：

videoOrientation

这是我创建和添加新消息的方式

lazy var fetchedResultsController: NSFetchedResultsController<Message> = {
    let context = CoreDataManager.shared.persistentContainer.viewContext
    let request: NSFetchRequest<Message> = Message.fetchRequest()

    request.sortDescriptors = [
        NSSortDescriptor(key: "createdAt", ascending: true)
    ]
    request.fetchLimit = 40

    let frc = NSFetchedResultsController(fetchRequest: request, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)

    // fetch only messages with that recipient id of the chat.
    let recipientId = "\(chat!.recipientId)"
    request.predicate = NSPredicate(format: "recipientId == %@", recipientId)

    return frc
}()

聊天的ManagedObject具有lastMessage的属性，该属性的类型为Message（也是托管对象），我将新创建的消息设置为Chat的最后一条消息。问题出在那儿吗？这也是委托代码：

func createNewTextMessage(recipientId: String, content: String) {

    ...

    guard let id = Int32(recipientId) else { return }
    guard let chat = fetchSingleChat(recipientId: id) else { return }

    let context = persistentContainer.viewContext
    let message = Message(context: context)

    let date = Date()

    message.chatId = chat.id
    message.createdAt = date
    message.isRead = false
    message.senderId = Int32(currentUserId)
    message.senderName = currentUserName
    message.senderPhoneNumber = currentUserPhoneNumber
    message.status = MessageStatus.unsent.rawValue
    message.type = MessageType.text.rawValue
    message.owner = MessageOwnerType.mine.rawValue
    message.content = content
    message.recipientId = chat.recipientId
    message.recipientName = chat.title

    message.messageId = "\(currentUserToken)_\(date.millisecondsSince1970)"

    // here's where i'm setting some relationship (chat to message: 1-to-many)
    message.chat = chat 
    chat.lastMessage = message
    message.chat?.lastMessage = message

    do {
        try context.save()
    } catch let err {
        print("failed to save private chat:", err)
    }

}

Answer 1

请注意，您对移动行（.move）的处理只会移动一行，您应该实施它才能移动很多行。不确定这是否可以解决您的问题，取决于您的数据排序方式。

这是我实施.move

的方式

case .move:
    if let indexPath = indexPath {
        tableView.removeRows(at: IndexSet(integer: indexPath.item), withAnimation: .effectFade)
    }
    if let newIndexPath = newIndexPath {
        tableView.insertRows(at: IndexSet.init(integer: newIndexPath.item), withAnimation: .effectFade)
    }

NSFetchedResultsController无法正确更新tableView

1 个答案: