Post request with HTTP header parameters - ios

Question

I Want to use Bittrex api. I've read their api docs. There are explanations like the following.
For this version, we use a standard HMAC-SHA512 signing. Append apikey
and nonce to your request and calculate the HMAC hash and include it
under an apisign header.
$apikey='xxx';
$apisecret='xxx';
$nonce=time();
$uri='https://bittrex.com/api/v1.1/market/getopenorders?apikey='.$apikey.'&nonce='.$nonce;
$sign=hash_hmac('sha512',$uri,$apisecret);
$ch = curl_init($uri);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('apisign:'.$sign));
$execResult = curl_exec($ch);
$obj = json_decode($execResult);
I want to do this with Swift. But I don't want to use Alamofire.
I wrote a code. I think I'm doing everything but I'm getting the following error.
{
message = "APISIGN_NOT_PROVIDED";
result = "<null>";
success = 0;
}
I wrote similar code with Delphi. It works fine. So there is no problem with APIKEY. When I use the same parameters in Delphi, the same SecretHex is generated. So there's no problem with Encryption.
I think, I cannot do the Post Request with headers.
I can not find the fault. Would you please help me.
func getBalances()
{
let apiKeySTR = "01235xxxxxx"
let secretSTR = "41691xxxxxx"
let path = "https://bittrex.com/api/v1.1/account/"
let timeInterval = NSDate().timeIntervalSince1970
let epochtime = String(floor(timeInterval))
let urlFull = path + "getbalances" + "?" + "apikey=" + apiKeySTR + "&" + "nonce=" + epochtime
let secretUInt8 : [UInt8] = Array(urlFull.utf8)
var secretKey : [UInt8]?
do {
try secretKey = HMAC(key: secretSTR, variant: .sha512).authenticate(secretUInt8)
} catch {
print ("Error")
}
let secretHex = secretKey?.toHexString() ?? ""
guard let url = URL(string: urlFull) else { return }
var request = URLRequest(url: url)
request.addValue("apising", forHTTPHeaderField: (secretHex))
request.httpMethod = "POST"
let session = URLSession.shared
session.dataTask(with: request) { (data, response, error) in
if let response = response {
print(response)
}
if let data = data {
do {
let json = try JSONSerialization.jsonObject(with: data, options: [])
print(json)
} catch {
print(error)
}
}
}.resume()
}

Answer 1

First off... you have a typo:
request.addValue("apising", forHTTPHeaderField: (secretHex))
I believe it's apisign, not "apising", right?
And below is a recap on creating REST API requests with a header and body. You can update this method according your needs:
1) Create URLRequest
var request = URLRequest(url: requestURL)
2) Set headers and http method:
request.allHTTPHeaderFields = ["Authentication" : "Bearer XYZ..."]
request.httpMethod = "POST"
3) Set request body:
// parameters is a simple [String:String] dictionary, just as header
let jsonData = try? JSONSerialization.data(withJSONObject: parameters)
request.httpBody = jsonData
Complete example:
public enum RESTMethod:String {
case get = "GET"
case post = "POST"
case put = "PUT"
}
public func sendRequest(_ url: String,
method: RESTMethod,
headers: [String : String],
parameters: [String : Any],
completionHandler: #escaping (Data?, URLResponse?, Error?) -> Void) -> URLSessionTask! {
let requestURL: URL
if method == .get {
let parameterString = parameters.stringFromHttpParameters()
requestURL = URL(string:"\(url)?\(parameterString)")!
} else {
requestURL = URL(string: url)!
}
var request = URLRequest(url: requestURL)
request.allHTTPHeaderFields = headers
request.httpMethod = method.rawValue
if method == .post {
let jsonData = try? JSONSerialization.data(withJSONObject: parameters)
request.httpBody = jsonData
}
request.timeoutInterval = 60
let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
completionHandler(data,response,error)
}
task.resume()
return task
}
extension Dictionary {
/// Build string representation of HTTP parameter dictionary of keys and objects
func stringFromHttpParameters() -> String {
let parameterArray = self.map { (key, value) -> String in
let percentEscapedKey = (key as! String).addingPercentEncoding(withAllowedCharacters: CharacterSet.urlQueryAllowed)
let percentEscapedValue = (value as? String ?? "\(value)").addingPercentEncodingForURLQueryValue()!
return "\(percentEscapedKey)=\(percentEscapedValue)"
}
return parameterArray.joined(separator: "&")
}
}
Usage:
sendRequest("http://yourserver",
method: .get, // .post or .put
headers: [],
parameters: [],
completionHandler: { (data, response, error) in
// Handle response here
})