Unable to access values of type [AnyHashable:Any] - Swift 4

I am trying to access a particular value from a variable that is of type [AnyHashable: Any] however, I am getting an error while accessing any value. I have browsed the internet regarding this issue, but I did not get any specific solution for it. So is there any other way to access them? Please help and thanks in advance.

Function where I am getting an error

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
        if let messageID = userInfo[gcmMessageIDKey] {
            print("Message ID: \(messageID)")
        }
        //Print full message
        print(userInfo)

        guard let aps = userInfo[AnyHashable("gcm.notification.data")],
            let data = aps["filters"] as! String else { // Getting the error here
                return
        }
        print(aps)
        completionHandler(UIBackgroundFetchResult.newData)
    }

Fetched data on printing the userInfo

[AnyHashable("gcm.notification.data"): {"filters":"fjjnbbx zjbxzj","history":"dsfdxf","message":"value1","source":"message source"}]

I resolved the issue as the information I was receiving was of type NSString (JSON in String) not NSDictionary / [String : Any]. I have provided the working code that solved my problem below -

if let notificationData = userInfo["gcm.notification.data"] as? NSString {
                var dictionary : NSDictionary?
                if let data = notificationData.data(using: String.Encoding.utf8.rawValue) {
                    do {
                        dictionary = try JSONSerialization.jsonObject(with: data, options: []) as? NSDictionary
                        print("DICTIONARY : \(dictionary)")
                        if let dict = dictionary {
                            print(dict["alert_message"] as? String)
                            // ..... and so on
                        }
                    } catch let error as NSError {
                        print("Error: \(error)")
                    }
                }
            }