Swift basic event throttling - not debouncing!

Throttler.swift

class Throttler {

    private var currentTask: (() -> Void)?
    private var timer: Timer?
    private let minimumDelay: TimeInterval

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

    func call(_ task: @escaping () -> Void) {
        if(timer != nil) {
            // if timer did not finish tick just get the most recent event
            currentTask = task
        } else {
            // on tick execute and restart
            task()
            Timer.scheduledTimer(withTimeInterval: minimumDelay, repeats: false) { (t) in
                self.currentTask?()
                self.timer = nil
            }
        }
    }
}

// Usage

let throttler = Throttler(minimumDelay: 1)

@IBAction func volumeSliderChanged(_ sender: UISlider) {
    throttler.call {
        self.updateVolume()
    }
}