How do I create a NSTimer on a background thread?

Question

I have a task that needs to be performed every 1 second. Currently I have an NSTimer firing repeatedly every 1 sec. How do I have the timer fire in a background thread (no

Answer 1

My Swift 3.0 solution for iOS 10+, timerMethod() will be called in background queue.

class ViewController: UIViewController {

    var timer: Timer!
    let queue = DispatchQueue(label: "Timer DispatchQueue", qos: .background, attributes: .concurrent, autoreleaseFrequency: .workItem, target: nil)

    override func viewDidLoad() {
        super.viewDidLoad()

        queue.async { [unowned self] in
            let currentRunLoop = RunLoop.current
            let timeInterval = 1.0
            self.timer = Timer.scheduledTimer(timeInterval: timeInterval, target: self, selector: #selector(self.timerMethod), userInfo: nil, repeats: true)
            self.timer.tolerance = timeInterval * 0.1
            currentRunLoop.add(self.timer, forMode: .commonModes)
            currentRunLoop.run()
        }
    }

    func timerMethod() {
        print("code")
    }

    override func viewDidDisappear(_ animated: Bool) {
        super.viewDidDisappear(animated)
        queue.sync {
            timer.invalidate()
        }
    }
}