How can I use Timer formerly NSTimer in Swift

Question

I tried  var timer   NSTimer   timer timeInterval  0 01  target  self  selector  update  userInfo  nil  repeats  false    But  I got an error saying    timeInterval   T1  target  ViewController  selector     - gt      userInfo  NilType  repeats  Bool  - gt   T6  is not identical to  NSTimer

User · Accepted Answer

This will work    override func viewDidLoad         super viewDidLoad          Swift block syntax  iOS 10       let timer   Timer timeInterval  0 4  repeats  true      in print  Done             Swift  gt  3 selector syntax     let timer   Timer scheduledTimer timeInterval  0 4  target  self  selector   selector self update   userInfo  nil  repeats  true         Swift 2 2 selector syntax     let timer   NSTimer scheduledTimerWithTimeInterval 0 4  target  self  selector   selector MyClass update   userInfo  nil  repeats  true         Swift  lt 2 2 selector syntax     let timer   NSTimer scheduledTimerWithTimeInterval 0 4  target  self  selector   update   userInfo  nil  repeats  true        must be internal or public    objc func update            Something cool     For Swift 4  the method of which you want to get the selector must be exposed to Objective-C  thus  objc attribute must be added to the method declaration

User · Answer

Repeated event  You can use a timer to do an action multiple times  as seen in the following example  The timer calls a method to update a label every half second     Here is the code for that   import UIKit  class ViewController  UIViewController        var counter   0     var timer   Timer         IBOutlet weak var label  UILabel          start timer      IBAction func startTimerButtonTapped sender  UIButton            timer invalidate      just in case this button is tapped multiple times             start the timer         timer   Timer scheduledTimer timeInterval  0 5  target  self  selector   selector timerAction   userInfo  nil  repeats  true                stop timer      IBAction func cancelTimerButtonTapped sender  UIButton            timer invalidate                 called every time interval from the timer     func timerAction             counter    1         label text      counter             Delayed event  You can also use a timer to schedule a one time event for some time in the future  The main difference from the above example is that you use repeats  false instead of true   timer   Timer scheduledTimer timeInterval  2 0  target  self  selector   selector delayedAction   userInfo  nil  repeats  false    The above example calls a method named delayedAction two seconds after the timer is set  It is not repeated  but you can still call timer invalidate   if you need to cancel the event before it ever happens   Notes   If there is any chance of starting your timer instance multiple times  be sure that you invalidate the old timer instance first  Otherwise you lose the reference to the timer and you can t stop it anymore   see this Q amp A  Don t use timers when they aren t needed  See the timers section of the Energy Efficiency Guide for iOS Apps    Related   How to work with dates and time in Swift

User · Answer

timer   Timer scheduledTimer timeInterval  1  target  self  selector   selector createEnemy   userInfo  nil  repeats  true    And Create Fun By The Name createEnemy  fund createEnemy      do anything

User · Answer

As of iOS 10 there is also a new block based Timer factory method which is cleaner than using the selector           Timer scheduledTimer withTimeInterval  5  repeats  false    timer in         label isHidden   true

User · Answer

I tried to do in a NSObject Class and this worked for me   DispatchQueue main asyncAfter deadline   now      milliseconds 300       print  Bang

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for swift 3 and Xcode 8 2  nice to have blocks  but if You compile for iOS9 AND want userInfo                 self timer   Timer fireAt  fire                             interval  deltaT                             target  self                             selector   selector timerCallBack timer                                userInfo    custom   data                               repeats  true           RunLoop main add self timer   forMode  RunLoopMode commonModes          self timer  fire      func timerCallBack timer  Timer            let info   timer userInfo         print info

User · Answer

Updated to Swift 4  leveraging userInfo   class TimerSample        var timer  Timer       func startTimer             timer   Timer scheduledTimer timeInterval  5 0                                       target  self                                       selector   selector eventWith timer                                          userInfo     foo     bar                                          repeats  true                Timer expects  objc selector      objc func eventWith timer  Timer             let info   timer userInfo as Any         print info

User · Answer

SimpleTimer  Swift 3 1   Why   This is a simple timer class in swift that enables you to    Local scoped timer Chainable One liners Use regular callbacks   Usage   SimpleTimer interval  3 repeats  true  print  tick    start    Ticks every 3 secs   Code   class SimpleTimer     lt --was named Timer  but since swift 3  NSTimer is now Timer       typealias Tick     - gt Void     var timer Timer      var interval TimeInterval   in seconds       var repeats Bool     var tick Tick      init  interval TimeInterval  repeats Bool   false  onTick  escaping Tick           self interval   interval         self repeats   repeats         self tick   onTick           func start            timer   Timer scheduledTimer timeInterval  interval  target  self  selector   selector update   userInfo  nil  repeats  true   swift 3 upgrade           func stop            if timer    nil  timer  invalidate                         This method must be in the public or scope              objc func update             tick

User · Answer

In Swift 3 something like this with  objc   func startTimerForResendingCode         let timerIntervalForResendingCode   TimeInterval 60      Timer scheduledTimer timeInterval  timerIntervalForResendingCode                           target  self                           selector   selector timerEndedUp                            userInfo  nil                           repeats  false         objc func timerEndedUp         output  timerHasFinishedAndCodeMayBeResended

User · Answer

You will need to use Timer instead of NSTimer in Swift 3   Here is an example   Timer scheduledTimer timeInterval  1       target  self       selector   selector YourController update        userInfo  nil       repeats  true       objc selector expected for Timer  objc func update            do what should happen when timer triggers an event

User · Answer

Swift 5  I personally prefer the Timer with the block closure        Timer scheduledTimer withTimeInterval  1  repeats  false        in           TODO  - whatever you want

User · Answer

Check with   Swift 2  var timer   NSTimer scheduledTimerWithTimeInterval 0 01  target  self  selector  Selector  update    userInfo  nil  repeats  true    Swift 3  4  5  var timer   Timer scheduledTimer timeInterval  0 01  target  self  selector   selector self update   userInfo  nil  repeats  true

User · Answer

NSTimer has been renamed to Timer in Swift 4 2   this syntax will work in 4 2   let timer   Timer scheduledTimer timeInterval  1 0  target  self  selector   selector UIMenuController update   userInfo  nil  repeats  true

User · Answer

First declare your timer  var timer  Timer    Then add line in viewDidLoad   or in any function you want to start the timer  timer   Timer scheduledTimer timeInterval  1  target  self  selector   selector action   userInfo  nil  repeats  false    This is the func you will callback it to do something it must be  objc   objc func action      print  done

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Swift 3  pre iOS 10  func schedule         DispatchQueue main async         self timer   Timer scheduledTimer timeInterval  20  target  self                                     selector   selector self timerDidFire timer     userInfo  nil  repeats  false                objc private func timerDidFire timer  Timer        print timer        Swift 3  iOS 10   DispatchQueue main async         self timer   Timer scheduledTimer withTimeInterval  20  repeats  false    timer in         print timer                  Notes   It needs to be on the main queue Callback function can be public  private      Callback function needs to be  objc

User · Answer

If you init method of timer   let timer   Timer timeInterval  3  target  self  selector   selector update       userInfo   key   value   repeats  false   func update   timer   Timer         then add it to loop using method other selector will not be called  RunLoop main add timer   forMode   defaultRunLoopMode    NOTE   If you are want this to repeat make repeats true and keep the reference of timer otherwise update method will not be called   If you are using this method   Timer scheduledTimer timeInterval  seconds  target  self  selector   selector update       userInfo  nil  repeats  true    keep a reference for later use if repeats is true

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