從這個viewcontroll 傳值到另外一個viewcontroller

利用   prepare 這個function


call 了  performSegue(withIdentifier: "gotoview2", sender: inputtext)

  @IBAction func changeView(_ sender: UIButton) {

        

        //check if user input text or not

        

        if let inputtext = myTextInput.text{

            if inputtext == ""{

                // no input, pop up an alert

                let myalert = UIAlertController(title: "No input", message: "Please enter something", preferredStyle: .alert)

                let okaction = UIAlertAction(title: "OK", style: .default, handler: nil)

                myalert.addAction(okaction)

                present(myalert, animated: true, completion: nil)

            }else{

                performSegue(withIdentifier: "gotoview2", sender: inputtext)

            }

            

        }

        

    }

然後系統就會自動呼叫   prepare()...  在這裡面判斷要去的   viewcontroll

在這裡我們要去    gotoview2 這個  viewcontroller

 override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

          if segue.identifier == "gotoview2"{

            if let lightred = segue.destination as? lightRedViewController{

                lightred.infoFromView1 = sender as? String

            }

          }

        

    }

    

把數值存到    gotoview2 這個  viewcontroller 的變數   infoFromView1

-------------------------------

class lightRedViewController: UIViewController {

    var infoFromView1:String?

    

    @IBOutlet weak var myLabel: UILabel!

    override func viewDidLoad() {

        super.viewDidLoad()

        

        myLabel.text = infoFromView1

        // Do any additional setup after loading the view.

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

    

    /*

    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        // Get the new view controller using segue.destinationViewController.

        // Pass the selected object to the new view controller.

    }

    */

}

-------------

回到剛剛的viewcontroll...

 let _ = navigationController?.popViewController(animated: true)

前提是有embed navigatorcontroller

--------------

 myTextInput.resignFirstResponder() // release the focus