Background fetch with Mailcore 2

AppDelegate.swift

class AppDelegate: UIResponder, UIApplicationDelegate {
  func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        
        let settings = UIUserNotificationSettings(types: UIUserNotificationType.alert, categories: nil)
        UIApplication.shared.registerUserNotificationSettings(settings)
        UIApplication.shared.setMinimumBackgroundFetchInterval(UIApplicationBackgroundFetchIntervalMinimum)
    
        return true
  }
  
  func applicationDidEnterBackground(_ application: UIApplication) {
    print("applicationDidEnterBackground")
  }
  
  func application(_ application: UIApplication,
                     performFetchWithCompletionHandler completionHandler:
        @escaping (UIBackgroundFetchResult) -> Void) {
        fetchUpdates(completionHandler: completionHandler)
  }
  
  func fetchUpdates(completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
        let session = MCOIMAPSession()
        session.hostname = "imap.gmail.com"
        session.port = 993
        session.username = "[email protected]"
        session.password = "********"
        session.connectionType = .TLS
        
        let requestKind = MCOIMAPMessagesRequestKind.headers
        let folder = "INBOX"
        let uids = MCOIndexSet(range: MCORange(location: 1, length: UInt64.max))
        
        let fetchOperation = session.fetchMessagesOperation(withFolder: folder, requestKind: requestKind, uids: uids)
        
        fetchOperation?.start({ (error, fetchedMessages, _) in
            if let error = error {
                print("Error \(error.localizedDescription)")
                completionHandler(.noData)
                return
            }
            
            if let messages = fetchedMessages {
                if messages.isEmpty {
                    print("No messages")
                    completionHandler(.noData)
                } else {
                    print("New messages \(messages.count)")

                    let localNotification: UILocalNotification = UILocalNotification()
                    localNotification.alertAction = "App Name"
                    localNotification.alertBody = "\(messages.count) new messages"
                    localNotification.fireDate = NSDate(timeIntervalSinceNow: 1) as Date
                    UIApplication.shared.scheduleLocalNotification(localNotification)

                    completionHandler(.newData)
                }
            } else {
                log.info("No messages (nil)")
                completionHandler(.noData)
            }
        })
    }
}