Detects the inactivity of a user based on a timer setup.

userInactivityDetector.swift

extension Notification.Name {

    public static let ProlongedInactivity = Notification.Name("ProlongedInactivity")
}

class UserInactivityDetector {

    var idleTimeAllowed: TimeInterval = 30 {
        didSet {
            if enabled {

                reinitThetimer()
            } else {

                workItem?.cancel()
            }
        }
    }

    private var workItem: DispatchWorkItem?

    var enabled: Bool = true {
        didSet {
            if enabled {

                reinitThetimer()
            } else {

                workItem?.cancel()
            }
        }
    }

    init() {

        NotificationCenter.default.addObserver(self, selector:#selector(onUserActivity), name: Notification.Name.SentEvent, object: nil)

        reinitThetimer()
    }

    func sendInactivityNotification() {

        NotificationCenter.default.post(name: Notification.Name.ProlongedInactivity, object: nil)
    }

    func reinitThetimer() {

        workItem?.cancel()
        workItem = DispatchWorkItem(block: { [weak self] in
            self?.sendInactivityNotification()
        })
        if let valid = workItem {
            DispatchQueue.main.asyncAfter(deadline: .now() + idleTimeAllowed, execute: valid)
        }
    }

    @objc func onUserActivity() {

        reinitThetimer()
    }
}