@IBAction func btnSignIn(_ sender: AnyObject) {

        //deklarasi variable
        let username:NSString = etUsername.text! as NSString
        let password:NSString = etPass.text! as NSString
        //pengecekan apabila nilai nya kosong
        if ( username.isEqual(to: "") || password.isEqual(to: "") ) {

            let alertView:UIAlertView = UIAlertView()
            alertView.title = "Sign in Failed!"
            alertView.message = "Please enter Username and Password"
            alertView.delegate = self
            alertView.addButton(withTitle: "OK")
            alertView.show()

        } else {

            do {
                let post:NSString = "username=\(username)&password=\(password)" as NSString

                NSLog("PostData: %@",post);

//                let url:NSURL = NSURL(string:"http://192.168.2.30/JsonLogin/jsonlogin2.php")!

                let url:URL = config.url as URL

                let postData:Data = post.data(using: String.Encoding.ascii.rawValue)!

                let postLength:NSString = String( postData.count ) as NSString

                let request:NSMutableURLRequest = NSMutableURLRequest(url: url)
                request.httpMethod = "POST"
                request.httpBody = postData
                request.setValue(postLength as String, forHTTPHeaderField: "Content-Length")
                request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
                request.setValue("application/json", forHTTPHeaderField: "Accept")


                var reponseError: NSError?
                var response: URLResponse?

                var urlData: Data?
                do {
                    urlData = try NSURLConnection.sendSynchronousRequest(request as URLRequest, returning:&response)
                } catch let error as NSError {
                    reponseError = error
                    urlData = nil
                }

                if ( urlData != nil ) {
                    let res = response as! HTTPURLResponse!;

//                    NSLog("Response code: %ld", res?.statusCode);
//
                    if ((res?.statusCode)! >= 200 && (res?.statusCode)! < 300)
                    {
                        let responseData:NSString  = NSString(data:urlData!, encoding:String.Encoding.utf8.rawValue)!

                        NSLog("Response ==> %@", responseData);

                        //var error: NSError?

                        let jsonData:NSDictionary = try JSONSerialization.jsonObject(with: urlData!, options:JSONSerialization.ReadingOptions.mutableContainers ) as! NSDictionary


                        let success:NSInteger = jsonData.value(forKey: "success") as! NSInteger

                        //[jsonData[@"success"] integerValue];

                        NSLog("Success: %ld", success);

                        if(success == 1)
                        {
                            NSLog("Login SUCCESS");

                            let prefs:UserDefaults = UserDefaults.standard
                            prefs.set(username, forKey: "USERNAME")
                            prefs.set(1, forKey: "ISLOGGEDIN")
                            prefs.synchronize()

                            self.dismiss(animated: true, completion: nil)
                        } else {
                            var error_msg:NSString

                            if jsonData["error_message"] as? NSString != nil {
                                error_msg = jsonData["error_message"] as! NSString
                            } else {
                                error_msg = "Unknown Error"
                            }
                            let alertView:UIAlertView = UIAlertView()
                            alertView.title = "Sign in Failed!"
                            alertView.message = error_msg as String
                            alertView.delegate = self
                            alertView.addButton(withTitle: "OK")
                            alertView.show()

                        }

                    } else {
                        let alertView:UIAlertView = UIAlertView()
                        alertView.title = "Sign in Failed!"
                        alertView.message = "Connection Failed"
                        alertView.delegate = self
                        alertView.addButton(withTitle: "OK")
                        alertView.show()
                    }
                } else {
                    let alertView:UIAlertView = UIAlertView()
                    alertView.title = "Sign in Failed!"
                    alertView.message = "Connection Failure"
                    if let error = reponseError {
                        alertView.message = (error.localizedDescription)
                    }
                    alertView.delegate = self
                    alertView.addButton(withTitle: "OK")
                    alertView.show()
                }
            } catch {
                let alertView:UIAlertView = UIAlertView()
                alertView.title = "Sign in Failed!"
                alertView.message = "Server Error"
                alertView.delegate = self
                alertView.addButton(withTitle: "OK")
                alertView.show()
            }
        }