如何使用NSTimer進行倒計時？

Question

如何使用Swift與NSTimer進行倒計時？

Answer 1

問題1：

@IBOutlet var countDownLabel: UILabel! 

var count = 10 

override func viewDidLoad() { 
    super.viewDidLoad() 

    var timer = NSTimer.scheduledTimerWithTimeInterval(0.4, target: self, selector: Selector("update"), userInfo: nil, repeats: true) 
} 

func update() { 
    if(count > 0) { 
     countDownLabel.text = String(count--) 
    } 
} 

問題2：

你都可以做。 SpriteKit是您用於場景，動畫等的SDK。簡單視圖應用程序是項目模板。他們不應該發生衝突

Answer 2

變量爲您定時器

var timer = 60 

的NSTimer以1.0爲間隔

var clock = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: "countdown", userInfo: nil, repeats: true) 

在這裏，您可以減少定時器

func countdown() { 
    timer-- 
} 

Answer 3

在雨燕3.0，這將工作：

var counter = 30 

override func viewDidLoad() { 
    super.viewDidLoad() 

    var _ = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(updateCounter), userInfo: nil, repeats: true) 
} 



func updateCounter() { 
    //you code, this is an example 
    if counter > 0 { 
     print("\(counter) seconds to the end of the world") 
     counter -= 1 
} 

Answer 4

讓倒計時程序的Xcode 8.1，斯威夫特3

import UIKit 
import Foundation 

class ViewController: UIViewController, UITextFieldDelegate { 

    var timerCount = 0 
    var timerRunning = false 

    @IBOutlet weak var timerLabel: UILabel! //ADD Label 
    @IBOutlet weak var textField: UITextField! //Add TextField /Enter any number to Countdown 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     //Reset 
     timerLabel.text = "" 
     if timerCount == 0 { 
      timerRunning = false 
     } 
} 

     //Figure out Count method 
    func Counting() { 
     if timerCount > 0 { 
     timerLabel.text = "\(timerCount)" 
      timerCount -= 1 
     } else { 
      timerLabel.text = "GO!" 

     } 

    } 

    //ADD Action Button 
    @IBAction func startButton(sender: UIButton) { 

     //Figure out timer 
     if timerRunning == false { 
     _ = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(ViewController.Counting), userInfo: nil, repeats: true) 
      timerRunning = true 
     } 

     //unwrap textField and Display result 
     if let countebleNumber = Int(textField.text!) { 
      timerCount = countebleNumber 
      textField.text = "" //Clean Up TextField 
     } else { 
      timerCount = 3 //Defoult Number to Countdown if TextField is nil 
      textField.text = "" //Clean Up TextField 
     } 

    } 

    //Dismiss keyboard 
    func keyboardDismiss() { 
     textField.resignFirstResponder() 
    } 

    //ADD Gesture Recignizer to Dismiss keyboard then view tapped 
    @IBAction func viewTapped(_ sender: AnyObject) { 
     keyboardDismiss() 
    } 

    //Dismiss keyboard using Return Key (Done) Button 
    func textFieldShouldReturn(_ textField: UITextField) -> Bool { 
     keyboardDismiss() 

     return true 
    } 

} 

https://github.com/nikae/CountDown-

Answer 5

斯威夫特3

private let NUMBER_COUNT_DOWN = 3 

var countDownLabel = UILabel() 
var countDown = NUMBER_COUNT_DOWN 
var timer:Timer? 


private func countDown(time: Double) 
{ 
    countDownLabel.frame = CGRect(x: 0, y: 0, width: 300, height: 300) 
    countDownLabel.font = UIFont.systemFont(ofSize: 300) 
    countDownLabel.textColor = .black 
    countDownLabel.center = CGPoint(x: self.view.frame.width/2, y: self.view.frame.height/2) 

    countDownLabel.textAlignment = .center 
    self.view.addSubview(countDownLabel) 
    view.bringSubview(toFront: countDownLabel) 

    timer = Timer.scheduledTimer(timeInterval: time, target: self, selector: #selector(updateCountDown), userInfo: nil, repeats: true) 
} 

func updateCountDown() { 
    if(countDown > 0) { 
     countDownLabel.text = String(countDown) 
     countDown = countDown - 1 
    } else { 
     removeCountDownLable() 
    } 
} 

private func removeCountDownLable() { 
    countDown = NUMBER_COUNT_DOWN 
    countDownLabel.text = "" 
    countDownLabel.removeFromSuperview() 

    timer?.invalidate() 
    timer = nil 
}