CoreData问题:-[NSManagedObject setValue:]:发送到实例的无法识别的选择器

I just started with CoreData yesterday, and I'm going crazy :( I created a project that uses CoreData (ticked the box -use CoreData). Created the entities, and then created the NSManagedObject classes for all the entities (I suppose they create the 'setter' and 'getter' methods for the entities).I just started with CoreData yesterday, and I'm