var xmppStream: XMPPStream?
    @IBAction func login () {
        setField(username, forKey: kXMPP.myJID)
        setField(password, forKey: kXMPP.myPassword)

        if let status = xmppStream!.authenticateWithPassword(password.text){
            print("authentication successful")
        } else{
            print("authentication failed")
        }

        do
        {
            //since you may call this more than once; re-name xstream
            //to something else such as, for example, status
            _ = try xmppStream!.authenticateWithPassword(password.text)
            print("authentication successful")
        }
        catch let error as NSError
        {
            print(error)
        }
    }