Delayed NSOperation

DelayedBlockOperation.swift

class DelayedBlockOperation: NSOperation {
	private var delay: NSTimeInterval = 0
	private var block: (() -> Void)? = nil
	private var queue: dispatch_queue_t = dispatch_get_main_queue()
	
	override var asynchronous: Bool { return true }
	override var executing : Bool {
		get { return _executing }
		set { 
			willChangeValueForKey("isExecuting")
			_executing = newValue 
			didChangeValueForKey("isExecuting")
		}
	}
	private var _executing : Bool = false
	
	override var finished : Bool {
		get { return _finished }
		set { 
			willChangeValueForKey("isFinished")
			_finished = newValue
			didChangeValueForKey("isFinished")
		}
	}
	private var _finished : Bool = false
	
	init(delay: NSTimeInterval, _ block: () -> Void) {
		self.delay = delay
		self.block = block
	}
	
	init(delay: NSTimeInterval, queue: dispatch_queue_t, _ block: () -> Void) {
		self.delay = delay
		self.queue = queue
		self.block = block
	}
	
	override func start() {
		let delayTime = dispatch_time(DISPATCH_TIME_NOW, Int64(Double(delay) * Double(NSEC_PER_SEC)))
		dispatch_after(delayTime, queue) {
			guard !self.cancelled else {
				self.finished = true
				return
			}
			guard let block = self.block else {
				self.finished = true
				return
			}
			self.executing = true
			block()
			self.finished = true
		}
	}
}


//	Usage:
//	let op = DelayedBlockOperation(delay: 10) {
//		print("Executing operation")
//	}
//	NSOperationQueue().addOperation(op)

//	If you cancel the operation with `op.cancel()` before the
//	delay, the block is not executed :)

Swift 2.x?