XML parsing enclosure in Swift

I am trying to do exactly this Objective C code in Swift but it keeps returning a nil value and crashing. I am just trying to capture the url of an mp3 file so I can play it in my app.

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString     *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
       if ([elementName isEqualToString:@"enclosure"]) {
          self.podcastURL = [attributeDict objectForKey:@"url"];
       }
    }

Here is my code

// End Parsing Function and load dictionary key with <title> <link> and <itunes:summary> elements
func parser(parser: NSXMLParser!, didEndElement elementName: String!, namespaceURI: String!, qualifiedName qName: String!) {

    if (elementName as NSString).isEqualToString("item") {

        if ftitle != "" {
            elements.setObject(ftitle, forKey: "title")
            //println(ftitle) // Lookey Loo
        }

        if (link != "") {
            elements.setObject(link, forKey: "link")
            //println(link) // Lookey Loo
        }


        if (fdescription != "") {
            elements.setObject(fdescription, forKey: "itunes:summary")
            //println(fdescription) // Lookey Loo
        }

        if (mystream != "") {
            elements.setObject(mystream, forKey: "enclosure")
            //println(mystream) // Lookey Loo
        }

        feeds.addObject(elements)

    }

}

// Append the text from the element to the dictionary key location
func parser(parser: NSXMLParser!, foundCharacters string: String!) {


    if element.isEqualToString("title"){
        ftitle.appendString(string)

    }else if element.isEqualToString("link"){
        link.appendString(string)

    }else if element.isEqualToString("itunes:summary"){
        fdescription.appendString(string)

    }else if element.isEqualToString("enclosure"){
        mystream.appendString(string)
        println(mystream)
    }

}

// Now reload all the data
func parserDidEndDocument(parser: NSXMLParser!) {
    self.tableView.reloadData()

}