快速从核心数据中获取数据时应用程序崩溃答案

【问题标题】：App getting crashed while fetching data from core data swift快速从核心数据中获取数据时应用程序崩溃
【发布时间】：2018-07-23 10:22:43
【问题描述】：

这是获取数据的完整代码。这是从核心数据中获取数据的代码。这里有什么问题？请帮助获取数据时出了什么问题

static func getChatMessagesForGroup( groupId : Double) -> [GroupConversationMessage]{
    AppDelegate.getAppDelegate().log.debug("\(groupId)")
    let managedContext = CoreDataHelper.getNSMangedObjectContext()

    var messages = [GroupConversationMessage]()
    var conversationObjects = [NSManagedObject]()
    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: GROUP_CONVERSATION_TABLE_NAME)
    let predicate = NSPredicate(format: "\(GroupConversationMessage.FLD_GROUP_ID) = %@", argumentArray: [StringUtils.getStringFromDouble(decimalNumber : groupId)])
    fetchRequest.predicate = predicate
    let sortDescriptor = NSSortDescriptor(key: GroupConversationMessage.FLD_TIME, ascending: true)
    var sortDescriptors = [NSSortDescriptor]()
    sortDescriptors.append(sortDescriptor)
    fetchRequest.sortDescriptors =  sortDescriptors
    DispatchQueue.main.sync {
        do {
            let results = try managedContext.fetch(fetchRequest)
            conversationObjects = results as! [NSManagedObject]
        } catch let error as NSError {
            AppDelegate.getAppDelegate().log.error("Could not fetch \(error), \(error.userInfo)")
        }
    }

   for i in 0 ..< conversationObjects.count  {
        let message = GroupConversationMessage()
        message.uniqueID = conversationObjects[i].value(forKey: QuickRideMessageEntity.UNIQUE_ID) as? String
        message.id = conversationObjects[i].value(forKey: GroupConversationMessage.FLD_ID) as! Double
        message.groupId = conversationObjects[i].value(forKey: GroupConversationMessage.FLD_GROUP_ID) as! Double
        message.senderId = conversationObjects[i].value(forKey: GroupConversationMessage.FLD_SENDER_ID) as! Double
        message.senderName = conversationObjects[i].value(forKey: GroupConversationMessage.FLD_SENDER_NAME) as? String
        message.message = (conversationObjects[i].value(forKey: GroupConversationMessage.FLD_MESSAGE) as! String)
        message.time = conversationObjects[i].value(forKey: GroupConversationMessage.FLD_TIME) as! Double
        messages.append(message)
    }
    return messages
}

【问题讨论】：

什么是崩溃错误？
@PrashantTukadiya 这是发生的崩溃消息 Fatal Exception: NSGenericException *** Collection <__nscfset:> was mutated while being enumerated.
如果您更改了任何实体，您需要重新安装应用程序。
你是否在stackoverflow中检查过类似的问题，例如stackoverflow.com/questions/38434129/…
@PrashantTukadiya 我检查过那个帖子，但它没有帮助

标签： ios swift core-data

【解决方案1】：

我不确定，但您在获取数据时尝试更新或保存，或者您的集合类型可能是不可变的并且您正在尝试对其进行变异。

【讨论】：