“Message” is not a subclass of NSManagedObject error

Question

I received a "Message" is not a subclass of NSManagedObject error after trying to click on a button in my app. The app compiles just fine and I can use every other part of my app. The interesting thing is that it runs just fine in iOS7 but crashes in iOS6. I have read to prefix my entity but since it is called in about 50 classes I am checking to see if there is a different solution. I am also curious why it works in iOS7 but not iOS6. Also If I delete the MessageUI.framework it works on iOS6 and iOS7.

Answer 1

I discovered that if I use the default on the CONFIGURATIONS/Default (Class is the same as the Entity name: my image example of "WebResource" that I would get an exception

 reason: '"WebResource" is not a subclass of NSManagedObject.'

at statement:

WebResource *entry = [NSEntityDescription insertNewObjectForEntityForName:@"WebResource" inManagedObjectContext:mymanagedObjectContext];

but all works fine if i change the Class to "NSManagedObject". I do not know why the default is not "NSManagedObject" :(

Answer 2

It seems some names just don't work for entities: Message , WebResource , BluetoothDevice (as of iOS 11).

Renaming the entity and associated class solved it for me.