A simple notification throttler using DispatchWorkItem

NotificationThrottler.swift

class NotificationThrottler {
    let notificationCenter: NotificationCenter
    let timeInterval: TimeInterval
    let handler: () -> Void
    private var workItem: DispatchWorkItem?

    deinit {
        notificationCenter.removeObserver(self)
    }

    init(handler: @escaping () -> Void,
         notificationCenter: NotificationCenter = .default,
         notificationName: Notification.Name,
         timeInterval: TimeInterval) {
        self.handler = handler
        self.notificationCenter = notificationCenter
        self.timeInterval = timeInterval

        notificationCenter.addObserver(self,
                                       selector: #selector(notificationPosted),
                                       name: notificationName,
                                       object: nil)
    }

    @objc func notificationPosted() {
        workItem?.cancel()
        workItem = DispatchWorkItem(block: handler)

        //we just created the work item, it is safe to force unwrap in this situation
        DispatchQueue.main.asyncAfter(deadline: .now() + timeInterval, execute: workItem!)
    }
}