CODEWITHSUNDEEP
iosswift
Ryan Sayles
Ryan Sayles

Reputation: 3441

Swift call timer from ViewController

I have a TimerManager class that I would like to access in multiple ViewControllers but I can't figure out a good way to do it. My code is as follows:

class TimerManager {

    private var timer: NSTimer
    private var timeRemaining: Int

    init(initialTime: Int) {
        self.timer = NSTimer()
        self.timeRemaining = initialTime
    }

    func startTimer() {
        self.timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: #selector(TimerManager.update), userInfo: nil, repeats: true)
    }

    func endTimer() {
        self.timer.invalidate()
    }

    func getTimeRemaining() -> Int {
        return self.timeRemaining
    }

    @objc func update() {
        if self.timeRemaining > 0 {
            self.timeRemaining = self.timeRemaining - 1
        }
        else {
            endTimer()
        }
    } 
}

In my ViewController I would like to be able to access my update() function to update a timer (which is a UILabel) on my actual page, but since my startTimer() function calls it every second, I don't know how to access update() every time it is called. I briefly looked into protocols but I'm not really sure how they work or if that would be useful in my case.

Any help would be appreciated!

Upvotes: 0

Views: 670

Answers (3)

Mussa Charles
Mussa Charles

Reputation: 4452

Below is one of the best implementations of Timer on the background queue I found from this article 

class RepeatingTimer {

    let timeInterval: TimeInterval

    init(timeInterval: TimeInterval) {
        self.timeInterval = timeInterval
    }

    private lazy var timer: DispatchSourceTimer = {
        let t = DispatchSource.makeTimerSource()
        t.schedule(deadline: .now() + self.timeInterval, repeating: self.timeInterval)
        t.setEventHandler(handler: { [weak self] in
            self?.eventHandler?()
        })
        return t
    }()

    var eventHandler: (() -> Void)?

    private enum State {
        case suspended
        case resumed
    }

    private var state: State = .suspended

    deinit {
        timer.setEventHandler {}
        timer.cancel()
        resume()
        eventHandler = nil
    }

    func resume() {
        if state == .resumed {
            return
        }
        state = .resumed
        timer.resume()
    }

    func suspend() {
        if state == .suspended {
            return
        }
        state = .suspended
        timer.suspend()
    }
}

Usage: -

In any of your ViewControllers

For example: -

class MyViewController: UIViewController {

// MARK: - Properties
 var timer: RepeatingTimer!

// MARK: - ViewController LifeCycle

override func viewDidLoad() {
        super.viewDidLoad()
     timer =  RepeatingTimer(timeInterval: 1)
        timer.eventHandler = {
            print("Timer called")
        }

}

Upvotes: 0

Callam
Callam

Reputation: 11539

class TimerManager {

    private var timer: NSTimer
    private var timeRemaining: Int
    private var intervalBlock: (TimerManager -> ())?

    init(initialTime: Int) {
        self.timer = NSTimer()
        self.timeRemaining = initialTime
    }

    func startTimer(intervalBlock: (TimerManager -> ())? = nil) {
        self.intervalBlock = self
        self.timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: #selector(TimerManager.update), userInfo: nil, repeats: true)
    }

    func endTimer() {
        self.intervalBlock = nil
        self.timer.invalidate()
    }

    func getTimeRemaining() -> Int {
        return self.timeRemaining
    }

    @objc func update() {
        if self.timeRemaining > 0 {
            self.timeRemaining = self.timeRemaining - 1
            intervalBlock()
        }
        else {
            intervalBlock()
            endTimer()
        }
    } 
}

Upvotes: 0

Christian Abella
Christian Abella

Reputation: 5797

As @sschale suggested, you can do this by using a singleton to ensure that you will be accessing the same instance anywhere in your code. To do this, you need to set the init to private and provide a static member variable to access your single instance.

class TimerManager 
{
    static let sharedInstance = TimerManager()

    private var timer: NSTimer
    private var timeRemaining: Int

    private init()
    {
        let initialTime = 1
        self.timer = NSTimer()
        self.timeRemaining = initialTime
    }
    private init(initialTime: Int) 
    {
        self.timer = NSTimer()
        self.timeRemaining = initialTime
    }

    ...
}

Then in your ViewControllers you can just call it like this:

TimerManager.sharedInstance.startTimer()

Upvotes: 1

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