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()
				}
			}
	}
}

nice!

@ShamylZakariya would you mind showing an example of how this works? (sorry, iOS beginner here)

@parris Something like...

let debounced = debounce(
    NSTimeInterval(0.25),
    queue: dispatch_get_main_queue(),
    {
      _ in
        //do work
    }
  )

Can someone pls explain how to cancel methods? I'm implementing Search as you type and a request shall only be sent if a user hasn't type for more than 1 second.
I tried this solution and set delay for 5 sec and if I type 3 letters in 2 seconds, i have still 3 requests (at the moment i send after each typed letter a request), but i just want to have one request.
There should be a way to "restart" the function. Thanks in advance.

Solved it here: http://stackoverflow.com/questions/28411644/search-as-you-type-swift/28412321#28412321

do you have a sample implementation?