             
             // custom transformer
             let transformer = NSValueTransformer(forName: valueTransformerName!)
-            
-            
-        }
-        
-        return 0
+        }
+        
+        return nil
     }
     
     func attributeValueForJSONCompatibleValue(JSONCompatibleValue: AnyObject, forAttribute attributeName: String) -> AnyObject? {

    }
}

internal extension NSDate {
    
    
}


        
        let attributeClassName = attributeDescription!.attributeValueClassName
        
        switch attributeClassName {
            
            // strings and numbers are standard json data types
            case "NSString", "NSNumber":
                return attributeValue
            
            case "NSDate":
                let date = attributeValue as NSDate
                return date.ISO8601String()
            
            case "NSData":
                let data = attributeValue as NSData
                return data.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.Encoding64CharacterLineLength)
        }
        
        // transformable value type
        if attributeDescription?.attributeType == NSAttributeType.TransformableAttributeType {
            
            // get transformer
            let valueTransformerName = attributeDescription?.valueTransformerName
