iOS8 + Parse + Facebook Login

sourceApplication is always nil?

    func application(application: UIApplication, openURL url: NSURL,
        sourceApplication: NSString, annotation: AnyObject) -> Bool {
            println(PFFacebookUtils.session().description)
            return FBAppCall.handleOpenURL(url, sourceApplication: "", //sourceApplication:sourceApplication,
                withSession:PFFacebookUtils.session())