Simple Swift Debouncer

debounce.swift

func debounce( delay:NSTimeInterval, #queue:dispatch_queue_t, action: (()->()) ) -> ()->() {
	
	var lastFireTime:dispatch_time_t = 0
	let dispatchDelay = Int64(delay * Double(NSEC_PER_SEC))
	
	return {
		lastFireTime = dispatch_time(DISPATCH_TIME_NOW,0)
		dispatch_after(
			dispatch_time(
				DISPATCH_TIME_NOW,
				dispatchDelay
			),
			queue) {
				let now = dispatch_time(DISPATCH_TIME_NOW,0)
				let when = dispatch_time(lastFireTime, dispatchDelay)
				if now >= when {
					action()
				}
			}
	}
}

class Debouncer: NSObject {
    
    let delay: TimeInterval
    let queue: DispatchQueue
    
    var lastFireTime: DispatchTime!
    
    init(delay: TimeInterval, queue: DispatchQueue) {
        self.delay = delay
        self.queue = queue
    }
    
    func debounce(action: @escaping (() -> Void)) {
        self.lastFireTime = DispatchTime.now()
        self.queue.asyncAfter(deadline: DispatchTime.now() + self.delay) {
            let now = DispatchTime.now()
            let when = self.lastFireTime + self.delay
            if now >= when {
                action()
            }
        }
    }
}