How can I make a countdown with NSTimer

Question

How can I make a countdown with an NSTimer using Swift

User · Answer

Swift 4  Timer scheduledTimer timeInterval  1 0  target  self  selector   selector self updateTime   userInfo  nil  repeats  true    Update function   objc func updateTime        debugPrint  jalan

User · Answer

Make Countdown app Xcode 8 1  Swift 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  gt  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  - gt  Bool           keyboardDismiss            return true            https   github com nikae CountDown-

User · Answer

Swift 5 with Closure  class ViewController  UIViewController        var secondsRemaining   30       IBAction func startTimer   sender  UIButton                 Timer scheduledTimer withTimeInterval  1 0  repeats  true     Timer  in         if self secondsRemaining  gt  0               print   quot   self secondsRemaining  seconds quot               self secondsRemaining -  1           else               Timer invalidate

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Swift 4 1 and Swift 5  The updatetime method will called after every second and seconds will display on UIlabel       var timer  Timer       var totalTime   60           private func startOtpTimer                 self totalTime   60             self timer   Timer scheduledTimer timeInterval  1 0  target  self  selector   selector updateTimer   userInfo  nil  repeats  true                      objc func updateTimer                 print self totalTime              self lblTimer text   self timeFormatted self totalTime     will show timer             if totalTime    0                   totalTime -  1     decrease counter timer               else                   if let timer   self timer                        timer invalidate                       self timer   nil                                               func timeFormatted   totalSeconds  Int  - gt  String           let seconds  Int   totalSeconds   60         let minutes  Int    totalSeconds   60    60         return String format   quot  02d  02d quot   minutes  seconds

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import UIKit  class ViewController  UIViewController        let eggTimes     quot Soft quot   300   quot Medium quot   420   quot Hard quot   720           var secondsRemaining   60       IBAction func hardnessSelected   sender  UIButton            let hardness   sender currentTitle           secondsRemaining   eggTimes hardness            Timer scheduledTimer timeInterval  1 0  target  self  selector               selector UIMenuController update   userInfo  nil  repeats  true             objc func countDown              if secondsRemaining  gt  0                print  quot   secondsRemaining  seconds  quot               secondsRemaining -  1

User · Answer

Variable for your timer  var timer   60   NSTimer with 1 0 as interval  var clock   NSTimer scheduledTimerWithTimeInterval 1 0  target  self  selector   countdown   userInfo  nil  repeats  true    Here you can decrease the timer  func countdown         timer--

User · Answer

Swift 5 another way  Resistant to interaction with UI  I would like to show a solution that is resistant to user interaction with other UI elements during countdown   In the comments I explained what each line of code means    var timeToSet   0  var timer  Timer           IBAction func btnWasPressed   sender  UIButton             Setting the countdown time       timeLeft   timeToSet         Disabling any previous timers        timer  invalidate           Initialization of the Timer with interval every 1 second with the function call        timer   Timer timeInterval  1 0  target  self  selector   selector countDown   userInfo  nil  repeats  true          Adding Timer to the current loop       RunLoop current add timer   forMode   common                objc func countDown           if timeLeft  gt  0            print timeLeft           timeLeft -  1        else               Timer stopping          timer  invalidate

User · Answer

In Swift 5 1 this will work   var counter   30  override func viewDidLoad         super viewDidLoad        Timer scheduledTimer timeInterval  1 0  target  self  selector   selector updateCounter   userInfo  nil  repeats  true        objc func updateCounter           example functionality     if counter  gt  0           print    counter  seconds to the end of the world           counter -  1

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XCode 10 with Swift 4 2  import UIKit  class ViewController  UIViewController       var timer   Timer      var totalSecond   10     override func viewDidLoad            super viewDidLoad          startTimer             func startTimer            timer   Timer scheduledTimer timeInterval  1  target  self  selector   selector updateTime   userInfo  nil  repeats  true            objc func updateTime              print timeFormatted totalSecond            if totalSecond    0              totalSecond -  1           else              endTimer                        func endTimer             timer invalidate              func timeFormatted   totalSeconds  Int  - gt  String           let seconds  Int   totalSeconds   60         return String format   0  02d   seconds

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Swift 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  gt  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

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For use in Playground for fellow newbies  in Swift 5  Xcode 11  Import UIKit  var secondsRemaining   10      Timer scheduledTimer withTimeInterval  1 0  repeats  true     Timer  in     if secondsRemaining  gt  0           print   quot   secondsRemaining  seconds quot           secondsRemaining -  1       else           Timer invalidate

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this for the now swift    5 0 and newst  var secondsRemaining   60   Timer scheduledTimer timeInterval  1 0  target  self  selector   selector updateCounter   userInfo  nil  repeats  true     objc func updateCounter        if secondsRemaining  gt  0       print    secondsRemaining  seconds        secondsRemaining -  1

User · Answer

Add this to the end of your code    and call startTimer function with a parameter of where you want to count down to    For example  2 hours to the future of the date right now  - gt  startTimer for  Date   addingTimeInterval 60 60 2   Click here to view a screenshot of iPhone Simulator of how it ll look extension ViewController       func startTimer for theDate  String                let todaysDate   Date           let tripDate   Helper getTripDate forDate  theDate          let diffComponents   Calendar current dateComponents   hour   minute   from  Date    to  tripDate          if let hours   diffComponents hour                       hoursLeft   hours                   if let minutes   diffComponents minute                       minutesLeft   minutes                   if tripDate  gt  todaysDate                       timer   Timer scheduledTimer timeInterval  1 00  target  self  selector   selector onTimerFires   userInfo  nil  repeats  true                    else                       timerLabel text    quot 00 00 00 quot                            objc func onTimerFires                 secondsLeft -  1                    timerLabel text    quot   hoursLeft    minutesLeft    secondsLeft  quot          timerLabel text   String format   quot  02d  02d  02d quot   hoursLeft  minutesLeft  secondsLeft          if secondsLeft  lt   0               if minutesLeft    0                               secondsLeft   59                 minutesLeft -  1                                          if minutesLeft  lt   0               if hoursLeft    0                               minutesLeft   59                 hoursLeft -  1                                          if hoursLeft    0  amp  amp  minutesLeft    0  amp  amp  secondsLeft    0                        timer invalidate

User · Answer

Swift4        IBOutlet weak var actionButton  UIButton       IBOutlet weak var timeLabel  UILabel      var timer Timer      var timeLeft   60  override func viewDidLoad         super viewDidLoad       setupTimer      func setupTimer         timer   Timer scheduledTimer timeInterval  1 0  target  self  selector   selector onTimerFires   userInfo  nil  repeats  true      objc func onTimerFires         timeLeft -  1     timeLabel text      timeLeft  seconds left       if timeLeft  lt   0           actionButton isEnabled   true         actionButton setTitle  enabled   for   normal          timer  invalidate           timer   nil           IBAction func btnClicked   sender  UIButton        print  API Fired

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Question 1    IBOutlet var countDownLabel  UILabel   var count   10  override func viewDidLoad         super viewDidLoad        var timer   Timer scheduledTimer timeInterval  0 4  target  self  selector   selector UIMenuController update   userInfo  nil  repeats  true     func update         if count  gt  0            countDownLabel text   String count--            Question 2   You can do both  SpriteKit is the SDK you use for scene  motion  etc  Simple View Application is the project template  They should not conflict

[xcode] How can I make a countdown with NSTimer?

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