处理来自服务器的JSON数据，并在CoreData中添加/更新对象 [英] Process JSON data coming from server and add/update the objects in CoreData
问题描述
我正在使用 coreData 的应用程式，我有两个实体，分别是资料夹和笔记。所以他们在文件夹 - >笔记之间一对多关系。即1个文件夹=许多注释。
我对文件夹使用了 fetch results controller ，它显示在UITableView上，当用户点击
>一切正常。这里的一切都是离线的。
现在我想与服务器同步此数据，以便我可以将此数据同步到多个设备。
我使用的是 NSURLConnection 是默认情况下异步，它有委托函数，它从服务器提供json数据。现在我正试图处理这个 JsonData ，并且我采用了 FindOrCreate 方法。所以如果文件夹/ Notes存在，那么只是更新它，否则创建新的并保存它的coreData。我使用相同的managedObject和后期进程发生在主线程。
面对的问题。 （这是真实世界的情况）
1）当拉动发生时，用户可能会添加新的文件夹/注释，UI应该响应，但在我< case UI stuck stuck
。因此，我想知道我们如何流畅地创建/更新来自服务器的新数据，UI也是响应式的。在后台队列中执行后处理，方法是使用
dispatch_async（dispatch_get_global_queue（0,0），^ {
}
但是这里我观察到的是，我得到一个崩溃，说
到未捕获异常NSGenericException，原因：'* 集合<__ NSCFSet：0x1557ecd0>在枚举时发生了变化。
这是一个常见的错误，这意味着你不能循环一个集合并修改它在同一时间。说你想循环和查找对象删除。不要在循环中删除，plAce事情在临时集合中删除，并在循环后删除它们。
I am working on app which uses coreData, I have two entities called folder and notes. So their is one to many relationship between folders-> notes. i.e 1 folder = many notes.
I have used fetch results controller for folders, and it is displayed on the UITableView, when user clicks a folder, he goes to notes table, which displays notes inside the particular folder.
User can add and delete folders/Notes.
Everything works fine. Everything here is offline.
Now I am trying to synchronise this data with server, so that I can sync this to multiple devices. I dont do a blind sync, I only sync the data which is changed.
I am using NSURLConnection which is by default asynchronous and it has delegate functions which gives json data from server.
Now I am trying to process this JsonData and I am following a FindOrCreate methodology. So if the folder/Notes exists, then just update it or else create the new one and save it the coreData. I am using the same managedObject and post process happens on the main thread.
Problems faced. (which are real world cases)
1) When the pull happens, user might be adding new folders/notes and the UI should be responsive, but in my case UI gets stuck. So I want to know how can we fluidly create/update new data coming from server and the UI is also responsive.
2) I tried doing the post process in background queue, by using
dispatch_async(dispatch_get_global_queue(0,0), ^{
}
But here what I observed is that, I get a crash, which says * Terminating app due to uncaught exception 'NSGenericException', reason: '* Collection <__NSCFSet: 0x1557ecd0> was mutated while being enumerated.'
This is a common error. It means that that you cannot loop a collection and modify it at the same time. Say you wish to loop and find objects to delete. Don't delete in the loop, plAce things to be deleted in a temporary collection, and delete them after the loop.
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