delay

delay.swift

@IBAction func printHello(_ sender: Any) {
    // 延迟
    if shouldWaitSwitch.isOn {
        Timer.scheduledTimer(withTimeInterval: 0.5, repeats: true, block: { [unowned self] (timer) in
            if self.shouldWaitSwitch.isOn { return }
            
            print("你好！")
            timer.invalidate()
        })
    }
    else {
        print("你好！")
    }
}

@IBOutlet weak var shouldWaitSwitch: UISwitch!