iOSWebserviceResponseViewController.swift

    func performRequestWithUsername(username: String, password: String) {
    
        let loginRequest = LoginRequest(userId: username, password: password)
        let json = loginRequest.toJSON()
        let urlRequest = NSMutableURLRequest(   URL: NSURL(string: "https://SWIFT-WEBSERVICE-URL/login")!, 
                                        cachePolicy: .ReloadIgnoringLocalCacheData, 
                                    timeoutInterval: 60)
        urlRequest.HTTPMethod = "POST"
        urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
        urlRequest.HTTPBody = try? json.rawData()

        let requestTask = NSURLSession.sharedSession().dataTaskWithRequest(urlRequest) { 
            (data: NSData?, responseHeader: NSURLResponse?, error: NSError?) -> Void in
            
            dispatch_async(dispatch_get_main_queue()) {
            
                if let err = error { // NO response available
                    self.backendTV.text = "update error: \(err)"
                }else{ //response available
                    let serverResponseStatusCode = (responseHeader as! NSHTTPURLResponse).statusCode
                    switch serverResponseStatusCode{
                        case 200: //STATUS_OK

                            let json = JSON(data: data ?? NSData())
                            let loginResponse = LoginResponse(json: json)
                            self.backendTV.text = loginResponse.text
         
                            //expected JSON-response structure
                            //                            {
                            //                                 "user":{
                            //                                            "text" : "530",
                            //                                       }
                            //                            }
                            
                        default:
                            self.backendTV.text = "\(responseHeader) \n StatusCode: \(serverResponseStatusCode)"
                    }
                }
            }
        }
        requestTask.resume()
    }