Wrong value for url from xml

I parse a xml with this structure :

 "title": "VIDEO. Philippines : six millions de fidèles à Manille pour la messe du pape François",
 "description": "Le pape François a célébré une messe géante, ce dimanche, au Rizal Park de Manille (Philippines), en présence de six millions de fidèles rassemblés sous une pluie battante. La tempête tropicale...",
 "pubDate": "Sun, 18 Jan 2015 09:05:00 +0100",
 "link": "http://ift.tt/1zpj2np",
 "enclosure": {
                    "_url": "http://ift.tt/1LCQuKV",
                    "_length": "76019",
                    "_type": "image/jpeg"
                }
            },

Here is my code :

 - (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string{

    if ([currentElement isEqualToString:@"title"]) {
        [currentTitle appendString:string];

   else if ([currentElement isEqualToString:@"enclosure"]) {

        [currentPhoto appendString:string];
    }



- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName{

if ([elementName isEqualToString:@"item"]) {

    [item setObject:currentTitle forKey:@"title"];
    [item setObject:currentPhoto forKey:@"url"];
    [stories addObject:[item copy]];

}

and the value of url which i obtained is :

url = "\n \n ";

If in xml i dont have an image , i obtain url="" ;