POST request with data in body with Alamofire 4

how is it possible to send a POST request with a data in the HTTP body with Alamofire 4? I used custom encoding at swift 2.3 it was working good. I converted my code swift 3 and I tried to paramater encoding but not working. This code :

public struct MyCustomEncoding : ParameterEncoding {
private let data: Data
init(data: Data) {
    self.data = data
}
public func encode(_ urlRequest: URLRequestConvertible, with parameters: Parameters?) throws -> URLRequest {

    var urlRequest = try urlRequest.asURLRequest()        
    do {            
            urlRequest.httpBody = data
            urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")

    } catch {
        throw AFError.parameterEncodingFailed(reason: .jsonEncodingFailed(error: error))
    }

    return urlRequest
}

and Alamofire request :

let enco : ParameterEncoding = MyCustomEncoding(data: ajsonData)
    Alamofire.request(urlString, method: .post , parameters: [:], encoding: enco , headers: headers).validate()
                .responseJSON { response in
                    switch response.result {
                    case .success:
                        print(response)

                        break
                    case .failure(let error):

                        print(error)
                    }
    }

You need to send request like below in swift 3

let urlString = "https://httpbin.org/get"

Alamofire.request(urlString, method: .post, parameters: ["foo": "bar"],encoding: JSONEncoding.default, headers: nil).responseJSON {  
response in
  switch response.result {
                case .success:
                    print(response)

                    break
                case .failure(let error):

                    print(error)
                }
}

Swift 5 with Alamofire 5:

AF.request(URL.init(string: url)!, method: .post, parameters: parameters, encoding: JSONEncoding.default, headers: headers).responseJSON { (response) in
        print(response.result)

        switch response.result {

        case .success(_):
            if let json = response.value
            {
                successHandler((json as! [String:AnyObject]))
            }
            break
        case .failure(let error):
            failureHandler([error as Error])
            break
        }
    }