Upload image to Flickr

I am trying to upload image to Flickr from my app. I have referred some Objective-C code to do so but with no success.

The code I am using currently is:

func calUploadImageAPI(image:UIImage){    DispatchQueue.main.async(execute: {    })    var resultFromServer: Any?    var body : Data = Data()    var boundry = String()    boundry = NSUUID().uuidString    // Request    //    var request = URLRequest(url:URL(string:"https://up.flickr.com/services/upload/")!)    request.setValue("multipart/form-data; boundary=\(boundry)", forHTTPHeaderField: "Content-Type")    request.timeoutInterval = 150.0    request.httpMethod="POST"    var fileData = NSData()    fileData = UIImagePNGRepresentation(image)! as NSData    //proceed with resume upload    let md5Data = MD5(string:"\(userAuthSecret)api_key\(userKey)auth_token\(userAuthToken)")    let md5Hex =  md5Data!.map { String(format: "%02hhx", $0) }.joined()    body.append(String("--\(boundry)\r\n").data(using: String.Encoding.utf8)!)    body.append(String("Content-Disposition: form-data; name=\"api_key\"\r\n\r\n\(userKey)\r\n").data(using: String.Encoding.utf8)!)    body.append(String("--\(boundry)\r\n").data(using: String.Encoding.utf8)!)    body.append(String("Content-Disposition: form-data; name=\"auth_token\"\r\n\r\n\(userAuthToken)\r\n").data(using: String.Encoding.utf8)!)    body.append(String("--\(boundry)\r\n").data(using: String.Encoding.utf8)!)    body.append(String("Content-Disposition: form-data; name=\"api_sig\"\r\n\r\n\(md5Hex)\r\n").data(using: String.Encoding.utf8)!)    body.append(String("--\(boundry)\r\n").data(using: String.Encoding.utf8)!)    body.append(String("Content-Disposition: form-data; name=\"\("photo")\"; filename=\"\("profile_image.png")\"\r\n").data(using: String.Encoding.utf8)!)    body.append(String("Content-Type: image/jpeg\r\n\r\n").data(using: String.Encoding.utf8)!)    body.append(fileData as Data)    body.append(String("\r\n").data(using: String.Encoding.utf8)!)    body.append(String("--\(boundry)--\r\n").data(using: String.Encoding.utf8)!)    request.httpBody = body    //session    let configuration = URLSessionConfiguration.default    configuration.requestCachePolicy = .reloadIgnoringCacheData    let session : URLSession    session = URLSession(configuration: configuration, delegate: nil, delegateQueue: nil)    session.dataTask(with: request) { (data, resp, error) -> Void in        if error != nil {            DispatchQueue.main.async(execute: {            })        }else {            if data != nil {                let httpResponse: HTTPURLResponse = resp as! HTTPURLResponse                if httpResponse.statusCode == 200  || httpResponse.statusCode == 201 || httpResponse.statusCode == 202 || httpResponse.statusCode == 204 {                    do {                        resultFromServer = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.mutableContainers)                        if let respArr = resultFromServer as? NSArray{                            print("Resp Array:\(respArr)")                        }                        if let respDict = resultFromServer as? NSDictionary{                            print("Resp Dict:\(respDict)")                        }                        //post noif                        DispatchQueue.main.async(execute: {                            //post notif                            //no image? get newone                            //                                NSNotificationCenter.defaultCenter().postNotificationName(downloadimageURLNotif, object: nil)                        })                    } catch let error as NSError {                        print("ERROR: \(error.description)")                        DispatchQueue.main.async(execute: {                        })                    }                } else if httpResponse.statusCode == 401  || httpResponse.statusCode == 403 || httpResponse.statusCode == 498 || httpResponse.statusCode == 400 {                    //get msg                    do {                        resultFromServer = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.mutableContainers)                        if let respArr = resultFromServer as? NSArray{                            print("Resp Array:\(respArr)")                        }                        if let respDict = resultFromServer as? NSDictionary{                            print("Resp Dict:\(respDict)")                        }                        DispatchQueue.main.async(execute: {                        })                    } catch let error as NSError {                        print("ERROR: \(error.description)")                        DispatchQueue.main.async(execute: {                        })                    }                }            }        }        }.resume()}

And the md5 method is

 func MD5(string: String) -> Data? {        guard let messageData = string.data(using:String.Encoding.utf8) else { return nil }        var digestData = Data(count: Int(CC_MD5_DIGEST_LENGTH))        _ = digestData.withUnsafeMutableBytes {digestBytes in            messageData.withUnsafeBytes {messageBytes in                CC_MD5(messageBytes, CC_LONG(messageData.count), digestBytes)            }        }        return digestData    }

But I get the following error:

"<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n<rsp stat=\"fail\">\n\t<err code=\"98\" msg=\"Invalid auth token\" />\n</rsp>\n"

But I have cross checked and my tokens are correct. I obtain them using OAuthSwift project.