import UserNotifications

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    ...
    
    let userNotificationCenter = UNUserNotificationCenter.current()
    userNotificationCenter.delegate = self

    self.registerForPushNotifications()
	...
}

// MARK: - Notifications
    
func registerForPushNotifications() {
    UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .sound, .badge]) { (granted, _) in
        guard granted else { return }
        self.getNotificationSettings()
    }
}
    
func getNotificationSettings() {
    UNUserNotificationCenter.current().getNotificationSettings { (settings) in
        guard settings.authorizationStatus == .authorized else { return }
        DispatchQueue.main.async {
            UIApplication.shared.registerForRemoteNotifications()
        }
    }
}

extension AppDelegate: UNUserNotificationCenterDelegate {
    func userNotificationCenter(_ center: UNUserNotificationCenter,
                                willPresent notification: UNNotification,
                                withCompletionHandler
                                completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
        completionHandler(UNNotificationPresentationOptions.alert)
    }
    
    func userNotificationCenter(_ center: UNUserNotificationCenter,
                                didReceive response: UNNotificationResponse,
                                withCompletionHandler
                                completionHandler: @escaping () -> Void) {
        completionHandler()
    }
}

import MPushSwift

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    ...
    MPush.token = "YOUR_PUSH_TOKEN"
    ...
}

...

func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
    MPush.registerDevice(deviceToken: deviceToken, success: {
        MPush.register(toTopic: MPTopic("YOUR_TOPIC"))
        // OR if you have more than one topic
        // MPush.register(toTopics: [MPTopic("TOPIC1"), MPTopic("TOPIC2")])
    })
}

override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
    self.contentHandler = contentHandler
    bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)
    
    if let bestAttemptContent = bestAttemptContent {
        if let mediaUrl = request.content.userInfo["media_url"] as? String, let fileUrl = URL(string: mediaUrl) {
            downloadMedia(fileUrl: fileUrl, request: request, bestAttemptContent: bestAttemptContent) {
                contentHandler(bestAttemptContent)
            }
        } else {
            contentHandler(bestAttemptContent)
        }
    }
}
    
func downloadMedia(fileUrl: URL, request: UNNotificationRequest, bestAttemptContent: UNMutableNotificationContent, completion: @escaping () -> Void) {
    let task = URLSession.shared.downloadTask(with: fileUrl) { (location, _, _) in
        if let location = location {
            let tmpDirectory = NSTemporaryDirectory()
            let tmpFile = "file://".appending(tmpDirectory).appending(fileUrl.lastPathComponent)
            let tmpUrl = URL(string: tmpFile)!
            do {
                try FileManager.default.moveItem(at: location, to: tmpUrl)
                
                var options: [String: String]? = nil
                if let type = request.content.userInfo["media_type"] as? String {
                    options = [String: String]()
                    options?[UNNotificationAttachmentOptionsTypeHintKey] = type
                }
                if let attachment = try? UNNotificationAttachment(identifier: "media." + fileUrl.pathExtension, url: tmpUrl, options: options) {
                    bestAttemptContent.attachments = [attachment]
                }
                completion()
            } catch {
                completion()
            }
        }
    }
    task.resume()
}

override func serviceExtensionTimeWillExpire() {
    // Called just before the extension will be terminated by the system.
    // Use this as an opportunity to deliver your "best attempt" at modified content, otherwise the original push payload will be used.
    if let contentHandler = contentHandler, let bestAttemptContent =  bestAttemptContent {
        contentHandler(bestAttemptContent)
    }
}

if let attachment = try? UNNotificationAttachment(identifier: "media." + fileUrl.pathExtension, url: tmpUrl, options: options) {
    bestAttemptContent.attachments = [attachment]
}