add method to class subclassed from NSManagedObject

Question

I want to ad a methode to an object (subclassed from NSManagedObject)

@interface REMBox : NSManagedObject {
}
- (int)singleValueForIndex:(int)index;
@property (nonatomic,retain) NSString *name;    

but that methode can't be used

REMBox *box = ....
BOOL canCallMessage = [box respondsToSelector:@selector(singleValueForIndex:)];
// canCallMessage is NO
int a = [box singleValueForIndex:4];
// that crashes :-(

what's my fault. The normal (core-data) attributes of REMBox work well.

Answer 1

Did you set the new subclass REMBox as class to be used for your entity in your datamodel?

Class "Event" for entity "Event" in this sample. Never forget to make a clean rebuild (sometimes even reopen your xcode project) if core data does unexpected things.