class MyNetServiceDelegate : NSObject, NetServiceDelegate {
     public func netServiceDidResolveAddress(_ sender: NetService) {
        print(sender.hostName!, sender.port)
    }
}

static let ns = NetService(domain: "local.", type: "_http._tcp.", name: "myservice")

static var ns_deleg = MyNetServiceDelegate()

ns.delegate = ns_deleg
ns.resolve(withTimeout: TimeInterval(10))

ns.delegate = MyNetServiceDelegate()
ns.resolve(withTimeout: TimeInterval(10))