Timer.scheduledTimer Swift 3 pre-iOS 10 compatibility

Question

I need to schedule a Timer for firing a function every second but I see that in Xcode 8 beta 3 the scheduledTimer is only available for iOS 10.

Is there any alternative for using the timer in iOS 9 or previous versions?

Timer.scheduledTimer(withTimeInterval: 1, repeats: true, block: { (timer) in print("Hi!")})

score 57 · Answer 1 · edited Aug 03 '18 at 11:39

57

Solved using

Timer.scheduledTimer(timeInterval: 1,
                           target: self,
                         selector: #selector(self.updateTime),
                         userInfo: nil,
                          repeats: true)

edited Aug 03 '18 at 11:39

Haroldo Gondim

7,725
9
43
62

answered Aug 01 '16 at 10:05

rockdaswift

9,613
5
40
46

If you wish you can use `if #available(iOS 10, *) { //iOS 10 code } else { //iOS 9 code }` to support both depending on the OS version. – Awesomeness Feb 21 '17 at 21:41
I needed to add write the target function like this: `@objc func updateTime() {}` – Jonny Mar 29 '17 at 03:35
1

It's also worth looking at the lower posts to see how Timer's are stopped. It may not get removed from the run loop properly if it's not removed manually. – kbpontius Jun 11 '17 at 08:03
Hy I am new to swift, just a basic question, what does userInfo represents in scheduledTimer function?? – prasoonraj Dec 08 '21 at 04:41
Hi @prasoonraj, I guess that it means that you can pass a dictionary with any useful information every time the timer is fired. – rockdaswift Dec 08 '21 at 21:40

score 17 · Answer 2 · answered May 16 '17 at 06:06

Run a timer with swift3,

var timer: Timer?

func startTimer() {

    if timer == nil {
        timer = Timer.scheduledTimer(timeInterval: 3, target: self, selector: #selector(self.loop), userInfo: nil, repeats: true)
    }
}

func stopTimer() {
    if timer != nil {
        timer?.invalidate()
        timer = nil
    }
}

func loop() {
    let liveInfoUrl = URL(string: "http://192.168.1.66/api/cloud/app/liveInfo/7777")
    let task = URLSession.shared.dataTask(with: liveInfoUrl! as URL) {data, response, error in
        guard let data = data, error == nil else { return }
        print(String(data: data, encoding: String.Encoding(rawValue: String.Encoding.utf8.rawValue)) ?? "aaaa")
    }
    task.resume()
}

Release the timer when you not use it.

Once scheduled on a run loop, the timer fires at the specified interval until it is invalidated. A nonrepeating timer invalidates itself immediately after it fires. However, for a repeating timer, you must invalidate the timer object yourself by calling its invalidate() method.

Great job pointing out the `.invalidate()` end of Timer's, as well as the run loop. — kbpontius, Jun 11 '17 at 08:04
The nil check for timer is unnecessary. It is already an optional. — Adrian Bartholomew, Feb 26 '18 at 05:42

score 8 · Answer 3 · edited Mar 29 '20 at 09:11

Here is sample code workable with compatibility:

if #available(iOS 10.0, *) {
    Timer.scheduledTimer(withTimeInterval: 15.0, repeats: true){_ in
        // Your code is here:
        self.myMethod()
    }
} else {      
    Timer.scheduledTimer(timeInterval: 15.0, target: self, selector: #selector(self.myMethod), userInfo: nil, repeats: true)
}

//Your method or function:

// MARK: -  Method

@objc func myMethod() {
    print("Hi, How are you.")
}

score 3 · Answer 4 · answered Feb 03 '17 at 22:58

Swift 3

func runCode(in timeInterval:TimeInterval, _ code:@escaping ()->(Void))
{
    DispatchQueue.main.asyncAfter(
        deadline: .now() + timeInterval,
        execute: code)
}

func runCode(at date:Date, _ code:@escaping ()->(Void))
{
    let timeInterval = date.timeIntervalSinceNow
    runCode(in: timeInterval, code)
}

func test()
{
    runCode(at: Date(timeIntervalSinceNow:2))
    {
        print("Hello")
    }

    runCode(in: 3.0)
    {
        print("World)")
    }
}

score 3 · Answer 5 · answered Sep 27 '17 at 05:50

Updated for swift 3:

If you want to use Timer for some delay or any other purpose used below lines of code in your project;

// function defination:

func usedTimerForDelay()  {
    Timer.scheduledTimer(timeInterval: 0.3,
                         target: self,
                         selector: #selector(self.run(_:)),
                         userInfo: nil, 
                         repeats: false)
}

func run(_ timer: AnyObject) {
      print("Do your remaining stuff here...")

}

// function call:

self.usedTimerForDelay()

NOTE:- you can change the time interval as you want.

//Enjoy coding..!

score 1 · Answer 6 · answered May 12 '18 at 09:03

1

Timer.scheduledTimer

Put it in the main thread.

answered May 12 '18 at 09:03

senlinmu

141
2
11

score 1 · Answer 7 · answered Jun 02 '20 at 10:48

You can use the following simple shim to provide the new block-based Timers to pre-iOS 10:

class TimerShim {
    private var timer: Timer?
    private let block: (Timer) -> Void

    private init(timeInterval interval: TimeInterval, repeats: Bool, block: @escaping (Timer) -> Void) {
        self.block = block
        timer = Timer.scheduledTimer(timeInterval: interval, target: self, selector: #selector(timerDidFire), userInfo: nil, repeats: repeats)
    }

    class func scheduledTimer(withTimeInterval interval: TimeInterval, repeats: Bool, block: @escaping (Timer) -> Void) -> Timer {
        return TimerShim(timeInterval: interval, repeats: repeats, block: block).timer!
    }

    @objc private func timerDidFire() {
        block(timer!)
    }
}

Usage example:

TimerShim.scheduledTimer(withTimeInterval: 5, repeats: false) { _ in
    print("boom!")
}

score -5 · Answer 8 · answered Jan 27 '17 at 23:56

-5

The correct form is:

Timer.scheduledTimer(withTimeInterval: 2, repeats: false){_ in
   "Here your code method"
}

answered Jan 27 '17 at 23:56

Kike Gamboa

994
7
8

4

This is not running on iOS 9, but the question asked for < iOS 10 compatibility – hhamm Feb 03 '17 at 22:40
This code is working on swift 4.2 also.. Thanx for it. – Bijender Singh Shekhawat Nov 15 '18 at 11:18

Timer.scheduledTimer Swift 3 pre-iOS 10 compatibility

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