Swift 自动运行一个 NSTimer

Question

我正在制作一个应用程序并使用 NSTimer 在我的应用程序中制作计时器。但是我需要 NSTimer 在场景开始时运行。我的应用程序中有两个场景一个主屏幕，而它本身的应用程序是我的代码viewcontroller.swift（第二个场景第一个场景是空的）顺便说一句，这是我使用 swift 的第 3 天，我在中学；）。

 import UIKit
 var Number = 2
 var Answer = Number * 2
 var score = 0
var scorelabel = "Score: "
var Timer = NSTimer()
var Counter = 10

class SecondViewController: UIViewController {


@IBOutlet weak var RightAndWrongLabel: UILabel!

@IBOutlet weak var TimerLabel: UILabel!
@IBOutlet weak var RightAndWrong: UIImageView!
@IBOutlet weak var ScoreIabel: UILabel!
@IBOutlet weak var UserInputAnswer: UITextField!
@IBOutlet weak var Question: UILabel!
@IBOutlet weak var TimerOut: UIImageView!

var seconds = 0
var timeison = true







@IBAction func ConfirmAnswer(sender: AnyObject) {
    let UserAnswer = Int(UserInputAnswer.text!)
    if UserAnswer == Answer {
        print("Your right")
        Number += 2
        score += 1
        ScoreIabel.text = "Score: \(score)"
        Question.text = "\(Number) x 2"
        UserInputAnswer.text = ""
        Answer = Number * 2
        RightAndWrong.image = UIImage(named: "Label")
        RightAndWrongLabel.hidden = false
        RightAndWrongLabel.text = "Right!"
        RightAndWrongLabel.textColor  = UIColor(red: 0, green: 225, blue: 0, alpha: 1)

    } else {
        UserInputAnswer.text  = ""
        RightAndWrong.image = UIImage(named: "Label")
        RightAndWrongLabel.hidden = false
        RightAndWrongLabel.text = "Wrong!"
        RightAndWrongLabel.textColor = UIColor(red: 225, green: 0, blue: 0, alpha: 1)



    }



}

func DisplayTimer() {
    Timer = NSTimer.scheduledTimerWithTimeInterval(1, target:self, selector: Selector("updateCounter"), userInfo: nil, repeats: true)
}


func updateTimer(){
    TimerLabel.text = String(Counter--)
}
override func viewDidLoad() {
    super.viewDidLoad()
    UserInputAnswer.keyboardType = UIKeyboardType.NumberPad
    RightAndWrongLabel.hidden = true

    // Do any additional setup after loading the view.
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    3
    // 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 prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    // Get the new view controller using segue.destinationViewController.
    // Pass the selected object to the new view controller.
}
*/

}

Answer 1

Swift 2.x：

func DisplayTimer() {
    Timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target:self, selector: #selector(updateTimer), userInfo: nil, repeats: true)
}

func updateTimer() {
    if Counter != 0 {  TimerLabel.text = "\(Counter -= 1)" 
    } else { 
        Timer.invalidate() 
        // call a game over method here... 
    }
 }

override func viewDidLoad() {
    super.viewDidLoad()
   ... 

     // start the timer when this controller shows up
     DisplayTimer()
     TimerLabel.text = "\(Counter)" 

    ... 
   }

Answer 2

如果您想在场景加载时启动计时器，请调用 DisplayTimer() override func viewDidLoad() 加载视图时

此外，如果您想每秒更新一次标签，则 NSTimer 中的选择器调用 updateCounter 而不是 updateTimer