Darwin notifications in swift

gistfile1.swift

    // MARK: - Darwin Notifications

    static private let defaultsOnPhoneChangedDarwinNotificationName = "UserDefaultsOnPhoneDidChangeDarwinNotification"
    static private let defaultsOnWatchChangedDarwinNotificationName = "UserDefaultsOnWatchDidChangeDarwinNotification"

    static var notificationNameForReceiving: String?
    static var notificationNameForSending: String?

    /// Sets up the broadcast and receiving darwin notification names as well as
    /// as the necessary observer callbacks.
    static private func setupDarwinNotifications() {
        // Assume the only .appex bundle is the watch extension
        if NSBundle.mainBundle().bundleURL.pathExtension == "appex" {
            // Running inside an extension
            notificationNameForReceiving = defaultsOnPhoneChangedDarwinNotificationName
            notificationNameForSending = defaultsOnWatchChangedDarwinNotificationName
        }
        else {
            // Main app bundle
            notificationNameForReceiving = defaultsOnWatchChangedDarwinNotificationName
            notificationNameForSending = defaultsOnPhoneChangedDarwinNotificationName
        }
        registerForDarwinNotificationsWithIdentifier(notificationNameForReceiving!)
    }

    static private func registerForDarwinNotificationsWithIdentifier(identifier: String) {
        //func CFNotificationCenterAddObserver(_ center: CFNotificationCenter!,
        //    _ observer: UnsafePointer<Void>,
        //    _ callBack: CFNotificationCallback,
        //    _ name: CFString!,
        //    _ object: UnsafePointer<Void>,
        //    _ suspensionBehavior: CFNotificationSuspensionBehavior)

        //typealias CFNotificationCallback = CFunctionPointer<((CFNotificationCenter!, UnsafeMutablePointer<Void>, CFString!, UnsafePointer<Void>, CFDictionary!) -> Void)>

        let center = CFNotificationCenterGetDarwinNotifyCenter()

        let suspensionBehavior = CFNotificationSuspensionBehavior.DeliverImmediately
        // let suspensionBehavior = CFBooleanGetValue(true) // Session 224

        let callback: @objc_block
        (CFNotificationCenter!, UnsafeMutablePointer<Void>, CFString!, UnsafePointer<Void>, CFDictionary!) -> Void = {
            (center, observer, name, object, userInfo) in

            println("darwin callback")
            NSNotificationCenter.defaultCenter().postNotificationName(EBWUserDefaultsDidChangeNotification, object: nil,
                userInfo: nil)
        }
        let imp: COpaquePointer = imp_implementationWithBlock(unsafeBitCast(callback, AnyObject.self))
        let notificationCallback: CFNotificationCallback = CFunctionPointer(imp)

        CFNotificationCenterAddObserver(center,
            nil,
            notificationCallback,
            identifier,
            nil,
            suspensionBehavior)
    }

    static private func sendDarwinNotificationWithIdentifier(identifier: String) {
        let center = CFNotificationCenterGetDarwinNotifyCenter()
        let deliverImmediately: Boolean = Boolean()
        CFNotificationCenterPostNotification(center, identifier as CFString, nil, nil, deliverImmediately)
    }

I am also struggling for CFunctionPointer in swift. It is unavailable.