I'm a newbie in swift and I tried to make a Timer. It should normally count the seconds and print them in the debugger.
I tried this:
var timer = Timer()
#IBAction func killTimer(_ sender: AnyObject) {
timer.invalidate()
}
#objc func processTimer() {
print("This is a second")
}
override func viewDidLoad() {
super.viewDidLoad()
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(ViewController.processTimer), userInfo: nil, repeats: true)
}
I don't know how the timer count seconds.. With this code i get an fail message:
#objc func processTimer() {
print("This is second \(Timer + 1)")
}
Thanks for your help.
A
You need a counter variable which is incremented every time the timer fires.
Declare the variable Timer as optional to invalidate the timer reliably (only once).
var timer : Timer?
var counter = 0
#IBAction func killTimer(_ sender: AnyObject) {
timer?.invalidate()
timer = nil
}
#objc func prozessTimer() {
counter += 1
print("This is a second ", counter)
}
override func viewDidLoad() {
super.viewDidLoad()
timer = Timer.scheduledTimer(timeInterval:1, target:self, selector:#selector(prozessTimer), userInfo: nil, repeats: true)
}
You need to start your timer, you have only initialised it in your code so in viewDidLoad add
timer.fire()
I am not sure what you want to print but if it is a timestamp then you could do add a property to your class
let formatter = DateFormatter()
and configure it to show time in seconds and milliseconds
formatter.dateFormat = "ss.SSS" //in viewDidLoad
and use it in your print statement
print("This is a second \(formatter.string(from(Date())")
If you want to print the time that passed use this (If that's what you want):
print("time passed: \(Date().timeIntervalSince1970 - timer.fireDate.timeIntervalSince1970)")
Related
Full Disclosure: I am extremely new to everything swift/UIKit-related so I hope you can excuse my assured ignorance.
So the basic action I am trying to preform is having a Timer immediately begin a countdown the moment any character is entered into a UITextField (NOT triggered just by being focused).
Everything looks and functions 90% as I am intending except for an interaction where every time a character is entered into text field, the timer recursively initiates it's timeInterval.
After 7+ characters are typed, my 60-Second timer is far past 0 in less than a few seconds.
Using editingDidBegin "fixes" the issue but, in this parameter, the timer starts when the text field is tapped and focused and that isn't ideal for what I am trying to do.
My ViewController Code:
import UIKit
class SecondViewController: UIViewController, UITextFieldDelegate {
var textField: UITextField?
#IBOutlet weak var countDownLabel: UILabel!
var seconds = 60
var timer = Timer()
#IBAction func inputTextBar(_ sender: Any) {
func inputTextBar() {
self.becomeFirstResponder()
}
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(SecondViewController.counterb), userInfo: nil, repeats: true)
}
#objc func counterb() {
seconds -= 1
countDownLabel.text = String(seconds)
if seconds == 0 {
timer.invalidate()
countDownLabel.text = "Time's Up!"
}
}
var count = 10
override func viewDidLoad() {
super.viewDidLoad()
textField?.delegate = self
textField?.becomeFirstResponder()
}
}
Other Noted Confusion: If only one character is typed, the timer proceeds as normal and prints "Times Up!" at 0sec. and stops.
But if it's on the speed-pileup I mentioned, after a few characters are typed, the timer flies past 0 and never invalidates.
I assume that's a refresh issue.
Edit:
Okay, I figured out that making the timer variable weak I was able to get the timer to not keep stacking on itself. But, with the weak variable, the timer doesn't run at all while the UITextField is being typed in!
Semi-Fixed Code:
weak var timer: Timer?
#IBAction func inputTextBar(_ sender: AnyObject) {
timer?.invalidate()
timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(SecondViewController.loop), userInfo: nil, repeats: true)
}
#objc func loop() {
seconds -= 1
countDownLabel.text = String(seconds)
if self.seconds == 0 {
timer?.invalidate()
countDownLabel.text = "Time's Up!"
}
}
First change your timer declaration to optional. Then you can simply check if it is nil, if true schedule your timer. Second you should never rely on a timer to measure elapsed time. Just create an end date adding the desired time interval from now. This way you can simply check if now is greater or equal than the endDate when invalidating your timer. Use the timer only to update the UI and you can simply check the time interval since now when updating your label. The code below was written in the browser so it might have some mistakes but you can have an idea what to do to accomplish your goal.
class SecondViewController: UIViewController {
#IBOutlet weak var textField: UITextField!
#IBOutlet weak var countDownLabel: UILabel!
var endDate: Date? = nil
var timer: Timer? = nil
override func viewDidLoad() {
super.viewDidLoad()
textField.addTarget(self, action: #selector(editingChanged), for: .editingChanged)
textField.becomeFirstResponder()
}
#objc func editingChanged(_ textField: UITextField) {
if timer == nil {
timer = .scheduledTimer(timeInterval: 1,
target: self,
selector: #selector(counterb),
userInfo: nil,
repeats: true)
endDate = Date().addingTimeInterval(60)
}
}
#objc func counterb() {
countDownLabel.text = String(format: "%.0f", endDate!.timeIntervalSinceNow.rounded(.up))
if Date() >= endDate! {
timer?.invalidate()
timer = nil
endDate = nil
countDownLabel.text = "Time's Up!"
}
}
}
I am a school teacher and we have been 'ordered' to use a specific timer for our lessons, which low and behold doesn't work on our apple iMac's. I am trying to create my own in xcode and so far have created a basic window which will countdown a label in seconds. I have at the moment assigned the buttons and they work (in increments of 60 seconds).
This works and is fine but ideally i would like the label to display minutes and seconds instead (much easier for the kids). What is the best way to code this? Last time i used xcode was in 2009 and i am way out of date now!! Thanks in advance
--
#objc func updateTimer() {
seconds -= 1 //This will decrement(count down)the seconds.
countdownLabel.stringValue = "\(seconds)" //This will update the label.
}
--
#objc func runTimer() {
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector:(#selector(ViewController.updateTimer)), userInfo: nil, repeats: true)
}
--
#IBAction func threeMin(_ sender: Any) {
seconds = 180
runTimer()
}
--
There are many solutions. A convenient one is DateComponentsFormatter
let formatter : DateComponentsFormatter = {
let formatter = DateComponentsFormatter()
formatter.allowedUnits = [.minute, .second]
return formatter
}()
#objc func updateTimer() {
seconds -= 1
countdownLabel.stringValue = formatter.string(from: TimeInterval(seconds))!
}
Some improvements:
Assign tags to all buttons with their value in seconds for example set the tag of the threeMin button to 180. Then use only one IBAction and connect all buttons to that action.
In the action first check if the timer is running and start it only if it's not running
var timer : Timer?
#IBAction func startTimer(_ sender: NSButton) {
if timer == nil {
seconds = sender.tag
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(ViewController.updateTimer), userInfo: nil, repeats: true)
}
}
Create a function to stop the timer reliably
func stopTimer() {
if timer != nil {
timer?.invalidate()
timer = nil
}
}
In the updateTimer() function stop the timer if seconds is 0
#objc func updateTimer() {
seconds -= 1
countdownLabel.stringValue = formatter.string(from: TimeInterval(seconds))!
if seconds == 0 { stopTimer() }
}
I just started to learn swift . and I found when using a button to start a count down if i pressed the button twice it speeds up the process. What to add to prevent that?
#IBAction func startButton(_ sender: Any) {
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(processTime), userInfo: nil, repeats: true)
}
#objc func processTime(){
if counter > 0 {
counter -= 1
timeLabel.text = "\(counter)"
}else {
timer.invalidate()
}
}
I tried to use sender.isEnabled = false it gave this error (Value of type 'Any' has no member 'isEnabled')
so I did it like this :
#IBAction func startButton(_ sender: Any) {
if timer.isValid != true{
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(processTime), userInfo: nil, repeats: true)
}
}
Many ways, depends on what logic you prefer.
Basically you need to ensure that the timer starts only once until it completes.
In the following example, we start the timer only if it's not been initialized previously.
Furthermore, when we stop the timer, we explicitly set it to nil so the following logic works again after the timer completes.
//globally declared as optional
var timer: Timer?
#IBAction func startButton(_ sender: Any) {
//check if timer is nil
if timer != nil {
//start timer only if timer is nil
timer = Timer.scheduledTimer(timeInterval: 1,
target: self,
selector: #selector(processTime),
userInfo: nil,
repeats: true)
}
}
#objc func processTime() {
if counter > 0 {
counter -= 1
timeLabel.text = "\(counter)"
}
else {
timer.invalidate()
//clear the timer
timer = nil
}
}
add a sender.isEnabled = false and after you press the button once it won't be clickable again
You need to invalidate the timer by calling timer.invalidate() before you reassign a new timer. If you assign a new timer instance to the old one without invalidating, you will lose reference to it and it will never be invalidated.
Im trying to make a countdown timer. everything works fine except that my timer does not count at regular intervals (1sec); instead it counts all the way down instantly giving me 0 every time. did a lot of search without luck. All examples I could find show similar timeInterval parameter.
var timer = Timer()
var remainingTime = 120
#objc func timerCount () {
if remainingTime > 0 {
while remainingTime > 0 {
remainingTime -= 1
timerLabel.text = String(remainingTime)
print(remainingTime)
}
} else {
timer.invalidate()
}
}
#IBAction func pauseButton(_ sender: Any) {
timer.invalidate()
}
#IBAction func playButton(_ sender: Any) {
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.timerCount), userInfo: nil, repeats: true)
}
The reason your code is not working is that you have put an unnecessary while loop in your timerCount() method. You don't need to do this. Your timer will fire this method after each time interval. At very first call this while loop make your remainingTime to 0. This is why you are instantly getting 0 every time.
You just need to remove that while loop.
Can You try like this
var timer = Timer()
var remainingTime = 120
#objc func timerCount () {
let date = NSDate()
let nowdate = UserDefaults.standard.object(forKey: "NowDate") as! Date
let miniute = nowdate.timeIntervalSince(date as Date)
print(Int(miniute))
if (Int(miniute) == 0) {
timer.invalidate()
UserDefaults.standard.removeObject(forKey: "NowDate")
} else {
timerLabel.text = String(Int(miniute))
}
}
#IBAction func pauseButton(_ sender: Any) {
timer.invalidate()
UserDefaults.standard.removeObject(forKey: "NowDate")
}
#IBAction func playButton(_ sender: Any) {
let CurrentDate = NSDate()
let NowDate = CurrentDate.addingTimeInterval(TimeInterval(remainingTime))
UserDefaults.standard.set(NowDate, forKey: "NowDate")
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.timerCount), userInfo: nil, repeats: true)
}
After using
#IBAction func pauseButton(sender: AnyObject) {
if isPaused == false {
timer.invalidate()
isPaused = true
displayLabel.text = "\(count)"
println("App is paused equals \(isPaused)")
} else if isPaused == true {
var isPaused = false
timer.fire()
// timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("updateTime"), userInfo: nil, repeats: true)
}
}
to pause the app, i'd like to hit pause again, in which case, the timer will continue to count from where it left off.
Additionally, when i press pause/play too many times, multiple instances of the timer occur which will cause the timer to increase a few times per second.
Please help!
//
// ViewController.swift
// Navigation Bars
//
// Created by Alex Ngounou on 8/27/15.
// Copyright (c) 2015 Alex Ngounou. All rights reserved.
//
import UIKit
class ViewController: UIViewController {
var timer = NSTimer()
var count = 0
var isPaused = false
func updateTime() {
switch count {
case 0, 1:
count++
println( "\(count) second.")
displayLabel.text = "\(count)"
case 2:
count++
println("\(count) seconds.")
displayLabel.text = "\(count)"
default:
count++
println("\(count) seconds.")
displayLabel.text = "\(count)"
}
}
**strong text**#IBAction func playButton(sender: AnyObject) {
var isPaused = false
timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("updateTime"), userInfo: nil, repeats: true)
}
#IBAction func stopButton(sender: AnyObject) {
timer.invalidate()
count = 0
displayLabel.text = "0"
}
// if it's currently paused, pressing on the pause button again should restart the counter from where it originally left off.
#IBAction func pauseButton(sender: AnyObject) {
if isPaused == false {
timer.invalidate()
isPaused = true
displayLabel.text = "\(count)"
println("App is paused equals \(isPaused)")
} else if isPaused == true {
var isPaused = false
timer.fire()
// timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("updateTime"), userInfo: nil, repeats: true)
}
}
#IBAction func resetButton(sender: AnyObject) {
timer.invalidate()
count = 0
displayLabel.text = ""
}
#IBOutlet weak var displayLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("updateTime"), userInfo: nil, repeats: true)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
From: https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSTimer_Class/
Once invalidated, timer objects cannot be reused.
So essentially an NSTimer will do nothing at all once invalidated. Your timer property must be assigned to a newly constructed NSTimer object after that point to get it to fire again. If your invalidation bookkeeping is accurate, there is no "buildup" problem of multiple timers.
Probably the easiest method to your actual problem, though, is logical filtering. That is, keep the NSTimer object around indefinitely and let it fire continually. When the stored property isPaused is true, you ignore timer events (by returning immediately from the processing function), otherwise you process them.
a "lazier" approach can be otherwise useful:
class ViewController: UIViewController {
var timer: Timer?
override func viewDidLoad() {
super.viewDidLoad()
startTimer()
}
final func killTimer(){
self.timer?.invalidate()
self.timer = nil
}
final private func startTimer() {
// make it re-entrant:
// if timer is running, kill it and start from scratch
self.killTimer()
let fire = Date().addingTimeInterval(1)
let deltaT : TimeInterval = 1.0
self.timer = Timer(fire: fire, interval: deltaT, repeats: true, block: { (t: Timer) in
print("hello")
})
RunLoop.main.add(self.timer!, forMode: RunLoopMode.commonModes)
}
Declare your timer as 'weak var' like this:
weak var timer: Timer?