当我回到 Viewcontroller 时如何更改视图控制器的 label.text？

Question

喜欢我在这个问题中添加的图像。 我只是做了一个可以在现实生活中使用的计时器。 但有一些问题。 我可以将用户在第二个 setcontroller 中输入的数据扔给 Viewcontroller。 太棒了。但是当我回到视图控制器时，我只想让 viwcontroller'label.text 立即更改。为此，我做了几个功能，例如 viewWillAppear 或 viewdidappear.. 但是那东西不起作用..当我回到视图控制器时，如何立即更改视图控制器？请帮我。 我一直在等待你的意见。（很抱歉我的英语语法。） 我在下面添加我的代码.. 导入 UIKit

class ViewController: UIViewController {

    @IBOutlet var AllTileLabel: UILabel!
    @IBOutlet var SumTimeLabel: UILabel!
    @IBOutlet var CountTimeLabel: UILabel!
    @IBOutlet var StartButton: UIButton!
    @IBOutlet var StopButton: UIButton!
    @IBOutlet var ResetButton: UIButton!

    var timeTrigger = true
    var realTime = Timer()
    var second : Int = 3000
    var sum : Int = 0
    var allTime : Int = 28800
    var IntSecond : Int = 0
    var ifReset = false
    var data = TimeData()

    override func viewDidLoad() {

        StartButton.layer.cornerRadius = 10
        StopButton.layer.cornerRadius = 10
        ResetButton.layer.cornerRadius = 10

//        sum = UserDefaults.standard.value(forKey: "sum") as? Int ?? 0
//        allTime = UserDefaults.standard.value(forKey: "allTime") as? Int ?? 28800
//        second = UserDefaults.standard.value(forKey: "second") as? Int ?? 3000
//        
        sum = UserDefaults.standard.value(forKey: "sum2") as? Int ?? 0
        allTime = UserDefaults.standard.value(forKey: "allTime2") as? Int ?? 28800
        second = UserDefaults.standard.value(forKey: "second2") as? Int ?? 3000

        AllTileLabel.text = printTime(temp: allTime)
        CountTimeLabel.text = printTime(temp: second)
        SumTimeLabel.text = printTime(temp: sum)
//        getTimeData()

        super.viewDidLoad()
        // Do any additional setup after loading the view.

    }
    @IBAction func StartButtonAction(_ sender: UIButton) {
        if timeTrigger { checkTimeTrigger() }
        print("Start")
    }
    @IBAction func StopButtonAction(_ sender: UIButton) {
        endGame()
    }
    @IBAction func ResetButtonAction(_ sender: UIButton) {
        getTimeData() 
//        print("reset Button complite")
        second = UserDefaults.standard.value(forKey: "second") as! Int
        CountTimeLabel.text = printTime(temp: second)
        SumTimeLabel.text = printTime(temp: sum)
//        AllTileLabel.text = printTime(temp: allTime)
        print("print Time complite")
        ifReset = true
    }
    @IBAction func Reset(_ sender: UIButton) {
        endGame()
        timeTrigger = true
        realTime = Timer()
//        getTimeData() //data가 최신화
        print("reset Button complite")
        second = 3000
        sum = 0
        allTime = 28800
        IntSecond = 0
        ifReset = false

        AllTileLabel.text = printTime(temp: allTime)
        SumTimeLabel.text = printTime(temp: sum)
        CountTimeLabel.text = printTime(temp: second)
    }

    @objc func updateCounter(){
    //        if String(format: "%.2f",second) == "0.00"{
            if second < 1 {
                endGame()
                CountTimeLabel.text = "종료"
            } else {
                second = second - 1
                sum = sum + 1
                allTime = allTime - 1
                AllTileLabel.text = printTime(temp: allTime)
                SumTimeLabel.text = printTime(temp: sum)
                CountTimeLabel.text = printTime(temp: second)
                print("update")
                UserDefaults.standard.set(sum, forKey: "sum2")
                UserDefaults.standard.set(second, forKey: "second2")
                UserDefaults.standard.set(allTime, forKey: "allTime2")
            }
        }

    func checkTimeTrigger() {
        realTime = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateCounter), userInfo: nil, repeats: true)
        timeTrigger = false
    }

    func endGame() {
        realTime.invalidate()
        timeTrigger = true
    }

    func printTime(temp : Int) -> String
    {
        let S = temp%60
        let H = temp/3600
        let M = temp/60 - H*60

        let returnString = String(H) + ":" + String(M) + ":" + String(S)
        return returnString
    }

    func getTimeData(){
        second = UserDefaults.standard.value(forKey: "second") as? Int ?? 3000
        print("second set complite")
        allTime = UserDefaults.standard.value(forKey: "allTime") as? Int ?? 28800
        print("allTime set complite")
    }

}

Answer 1

viewWillAppear/viewDidAppear 在您以模态方式呈现第二个 vc 时不会被调用，因为您可以在返回时发送数据，然后在您关闭第二个 vc 并调用这样的函数时使用委托

func updateLbl(_ text:String){}

第一个vc里面

Answer 2

你可以使用闭包传回数据

 class DestinationViewController: UIViewController {
    var onCompletion: ((text: String) -> ())? // Add a closure onCompletion

 //either back button or dismiss button
    @IBAction func someButtonTapped(sender: AnyObject?) {
        onCompletion?(text:your text here) 
    }
}

class ViewController: UIViewController {
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

        guard let destinationController = segue.destinationViewController as? DestinationViewController else { return }

        destinationController.onCompletion = { text in
            // this will be executed when `someButtonTapped(_:)` will be called
            print(text)
        }
    }
}