String extension for getting Youtube id from URL

GetYTIdFromURL.swift

import Foundation

/*
this extension cover these case

www.youtube.com/v/id
www.youtube.com?v=vid
http://www.youtube.com/watch?v=id&feature=youtu.be
http://www.youtube.com/watch?v=id
youtube.be/id
http://www.youtube.com/watch?feature=player_detailpage&v=id#t=31s
www.youtube.com/watch?v=id&feature=youtu.be
www.youtube.com/watch?v=id
www.youtube.com/watch?feature=player_detailpage&v=id#t=31s
www.youtube.com/embed/id

from stackoverflow : http://stackoverflow.com/a/27796287

ex: 
let test = "https://www.youtube.com/embed/ZAF3u78Q9EM".parserYTIDFromURL()

console :
test = ZAF3u78Q9EM

*/

extension String {
    func parserYTIDFromURL() -> String {
        let pattern = "((?<=(v|V)/)|(?<=be/)|(?<=(\\?|\\&)v=)|(?<=embed/))([\\w-]++)"
        do{
            let regExp = try NSRegularExpression( pattern: pattern, options: NSRegularExpressionOptions.CaseInsensitive)
            let array = regExp.matchesInString(self, options: NSMatchingOptions(rawValue: 0), range: NSMakeRange(0, self.characters.count))
            if array.count > 0{
                let result: NSTextCheckingResult = array.first!
                return String((self as NSString).substringWithRange(result.range))
            }
        }catch{
            return ""
        }
        return ""
    }
}