pathExtension is unavailable: Use pathExtension on NSURL instead. Swift 2.0

Question

I get mp3 files from Document Directory, I wrote that pathExtension equals "mp3", in the Swift 1.2 it is working, but in the Swift 2.0 I get the error " 'pathExtension' is unavailable: Use pathExtension on NSURL instead."

 func fetchFilesFromFolder() {
        let fileManager = NSFileManager.defaultManager()
        let folderPathURL = fileManager.URLsForDirectory(NSSearchPathDirectory.DocumentDirectory, inDomains: NSSearchPathDomainMask.UserDomainMask)[0]
        if let directoryURLs = try? fileManager.contentsOfDirectoryAtURL(folderPathURL, includingPropertiesForKeys: nil, options: NSDirectoryEnumerationOptions.SkipsHiddenFiles) {
            listOfMP3Files = directoryURLs.map(){ $0.lastPathComponent! }.filter(){ $0.pathExtension == "mp3" } // error is here
        }
    }

Answer 1

Or you can use this extension:

extension String {
    var ns: NSString {
        return self as NSString
    }
    var pathExtension: String {
        return ns.pathExtension
    }
    var lastPathComponent: String {
        return ns.lastPathComponent
    }
}