JSonDecoder() Swift 4 Decoding error - json

Question

I am getting an error when trying to decode Json in swift 4
typeMismatch(Swift.Dictionary, Swift.DecodingError.Context(codingPath: [Swift._DictionaryCodingKey(stringValue: "ThrottleSeconds", intValue: nil)], debugDescription: "Expected to decode Dictionary but found a number instead.", underlyingError: nil))
Json reply is
{"Response":"4611686018456390681","ErrorCode":1,"ThrottleSeconds":0,"ErrorStatus":"Success","Message":"Ok","MessageData":{}}
struct BasicReply: Decodable {
let Response : String?
let ErrorCode : Int?
let ThrottleSeconds : Int?
let ErrorStatus : String?
let Message : String?
let MessageData : String?
}
class NetworkRequests {
let api = apiDetails()
func buildRequests()->String{
let request = "1/Stats/GetMembershipIdByDisplayName/" + api.userName + "/"
// let request = "1/Account/" + api.membershipId + "/Summary/"
return request
}
func request(){
let destinyURL : String = api.destinyURL + buildRequests()
let url = NSURL(string: destinyURL)
let request = NSMutableURLRequest(url: url! as URL)
request.httpMethod = "GET"
// add headers
request.setValue(api.apiKey, forHTTPHeaderField: "X-API-Key")
let session = URLSession.shared
let destinySession = session.dataTask(with: request as URLRequest) { (data, response, error) -> Void in
if let response = response as? HTTPURLResponse {
let code = response.statusCode
print(code)
}
guard let data = data else {print("No DATA!!!");return}
let output = String(data: data, encoding: String.Encoding.utf8)
print("output ", output! as Any)
do {
let questions = try JSONDecoder().decode([String: BasicReply].self, from: data)
} catch let jsonErr {
print("Error decoding Json Questons", jsonErr)
}
}
destinySession.resume()
}
}