Any class you have which conforms to the NSCoding protocol can be serialized and archived in this way. NSArray/NSMutableArray already conform this protocol. Its important to say that all of objects of the array must conform too.
If you have in your model an entity with a property of type 'Binary Data', you can store in it the array data by doing:
[...] NSData *arrayData = [NSKeyedArchiver archivedDataWithRootObject:TheArray]; myEntity.arrayProperty = arrayData; [self saveContext]; //Self if we are in the model class [...]
Then you can retrieve all the original array info by doing the opposite operation:
[...] NSMutableArray *array = [NSKeyedUnarchiver unarchiveObjectWithData:anEntity.arrayProperty]; [...]