insertNewObjectForEntityForName：inManagedObjectContext：返回NSNumber错误？

我相对精通CoreData，并且几年来一直使用它很少或没有困难。对于我的生活，我无法弄清楚为什么

I'm relatively well versed in CoreData and have been using it for several years with little or no difficulty. For the life of me, I can't figure out why

insertNewObjectForEntityForName:inManagedObjectContext:

突然返回某种奇怪的NSNumber实例。 GDB说返回的对象是NSManagedObject的正确自定义子类，但是当我去打印NSManagedObject本身的描述时，我收到以下错误：

is all of a sudden returning some sort of strange instance of NSNumber. GDB says the returned object is of the correct custom subclass of NSManagedObject, but when I go to print a description of the NSManagedObject itself, I get the following error:

*** -[NSCFNumber objectID]: unrecognized selector sent to instance 0x3f26f50

更奇怪的是，我能够使用setValue设置一些关系和属性：forKey：一切都很好。但是当我尝试设置一个特定关系时，我收到此错误：

What's even stranger, is that I'm able to set some relationships and attributes using setValue:forKey: and all is good. But when I try to set one specific relationship, I get this error:

*** -[NSCFNumber entity]: unrecognized selector sent to instance 0x3f26f50

我已尝试从干净的所有目标到重启mac和iPhone，甚至编辑模型，以便所讨论的关系是一个而不是多个。无论我做什么，都会出现同样的问题。有没有人见过这样的事情？

I've tried everything from clean all targets, to restarting both mac and iPhone, even editing the model so that the relationship in question is to-one instead of to-many. No matter what I do, the same problem appears. Has anyone ever seen anything like this before?