Suppose you want to upload an image with key named as userImage, then you can use multipart feature of Alamofire. I have used SwiftyJSON here. You can modify as per your own requirement.
var parameters: [String:Any]?
//fill your parameters with data. Image is stored as Data and other values are string in this case.
Alamofire.upload(multipartFormData: { (multipartFormData:MultipartFormData) in
        for (key, value) in parameters! {
            if key == "userImage" {
                multipartFormData.append(
                    value as! Data,
                    withName: key,
                    fileName: "profileImage.jpg",
                    mimeType: "image/jpg"
                )
            } else {
                //multipartFormData
                multipartFormData.append((value as! String).data(using: .utf8)!, withName: key)
            }
        }
    }, usingThreshold: 1, to: "yourServiceURL", method: .post, headers: ["yourHeaderkey":"value"]) { (encodingResult:SessionManager.MultipartFormDataEncodingResult) in
        switch encodingResult {
        case .success(let upload, _, _):
            upload.responseJSON { response in
                if response.result.error != nil {
                    return
                }
                if let data = response.result.value {
                    let json = JSON(data)
                }
            }
            break
        case .failure(let encodingError):
            debugPrint(encodingError)
            break
      }
  }