func startGADInterstitial(completion: (() -> Void)!){ } // completion option 1startGADInterstitial(completion: nil }) // completion option 2startGADInterstitial(completion: { () -> Void in }) ============================================================================ typealias CompletionHandler = (success:Bool) -> Void func downloadFileFromURL(url: NSURL,completionHandler: CompletionHandler) { ..
There is simple example timer in swift 3.0 class ViewController: UIViewController { var Timer :Foundation.Timer = Foundation.Timer() override func viewDidLoad() { Timer = Foundation.Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(ViewController.UpdateTimer), userInfo: nil, repeats: true) } func UpdateTimer(){ //Do something up to you } @IBAction func onClickedStopStart(_ ..