Swift global notifications

swift-global-notifications.swift

// AppDelegate.swift

// subscription listener subscribing to "some-event-name" posted by Electron or other app
func observer() {
    CFNotificationCenterAddObserver(CFNotificationCenterGetDistributedCenter(), Unmanaged.passRetained(self).toOpaque(), observerCallback, "some-event-name" as CFString , nil, .deliverImmediately)
}

// the listener callback - do something when you receive "some-event-name" event.
let observerCallback: CFNotificationCallback = { center , observer, name, object, info in
    // perform check on incoming data to see if it exists as a dictionary (object sent from javascript)
    if let data = info as? Dictionary<String, Any> {
     // Check if value present before using it
      guard let method = data["foo"] as? String else { return }
      print(method)
      // we can also post a event back
      postNotification()
    } else {
      print("Could not parse incoming data")
    }
  }

func postNotification() {
  // create notification event name that other apps will listen to
  let notificationName: CFNotificationName = .init(rawValue: "some-event-name" as CFString)
  // emit notification with data dictionary with key-value as String types
  let data: [String:String] = ["foo":"bar"]
  CFNotificationCenterPostNotification(CFNotificationCenterGetDistributedCenter(), NotificationName, nil, data as CFDictionary, true)
}