// Push notification

if #available(iOS 10.0, *) {
            let center = UNUserNotificationCenter.current()
            center.requestAuthorization(options: [.badge, .alert , .sound]) { (granted, error) in
                UIApplication.shared.registerForRemoteNotifications()
            }
        } else {
            let type: UIUserNotificationType = [UIUserNotificationType.badge, UIUserNotificationType.alert, UIUserNotificationType.sound]
            let setting = UIUserNotificationSettings(types: type, categories: nil)
            UIApplication.shared.registerUserNotificationSettings(setting)
            UIApplication.shared.registerForRemoteNotifications()
        }