iPhone iOS如何合并Core Data NSManagedObjectContext？ [英] iPhone iOS how to merge Core Data NSManagedObjectContext?

问题描述

我想在后台下载一些JSON对象，我做了相当多的多线程。一旦操作完成，我注意到这个断言失败：

I'm trying to download some JSON objects in the background and am doing quite a bit of multi threading. Once the operation completes, I noticed that this assertion fails:

NSAssert([user.managedObjectContext isEqual:[AppUser managedObjectContext]],@"Different contexts");

如何将更改合并到[AppUser managedObjectContext] strong>

How can I merge changes into the main context defined by [AppUser managedObjectContext] ?

推荐答案

在我的情况下，我使用RKObjectLoader的子类，有太多的线程和操作来跟踪的事情发生了。我发现RKObjectStore可以问我合并更改，通过要求加载对象保存自己。 （在我问 [AppUser managedObjectContext] 以保存自己，错误）之前

In my situation, I'm using a subclass of RKObjectLoader and there's way too many threads and operations to keep track of what's going on. I found that the RKObjectStore can be asked nicely to merge changes for me by asking the loaded object to save itself. (before I was asking [AppUser managedObjectContext] to save itself, which was wrong)

正确的解决方案涉及请求加载对象将其自身保存在自己的上下文中，如下所示：

The correct solution involved asking the loaded object to save itself in its own context as follows:

- (void)objectLoader:(RKObjectLoader*)objectLoader didLoadObjects:(NSArray*)objects {

    AppUser* user = nil;
    for (id object in objects)
    {
         user = object;
    }
    NSError* error = nil;


/**this call fires the:    
//    - (void)mergeChanges:(NSNotification *)notification
within the rkmanagedobjectstore class and merges changes made in this background operation over to the main contxt
 */
 [[user managedObjectContext] save:nil];

}

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