Status code 400 while making POST request in swift - swift

Question

I keep getting this error which I don't know how to resolve!
I'm trying to parse access token from a web API and for that I've set up post request.
Somehow it's throwing an error on 'responseString' line.
import UIKit
import Foundation
class ViewController: UIViewController, NSURLConnectionDelegate {
#IBOutlet var userName: UITextField!
#IBOutlet var password: UITextField!
#IBAction func submit(sender: AnyObject) {
let postString = "username=" + userName.text + "&password=" + password.text + "&grant_type=password";
let data: NSData = postString.dataUsingEncoding(NSUTF8StringEncoding)!
let base64LoginString = data.base64EncodedStringWithOptions(nil)
let postLength=NSString(format: "%ld", data.length)
let url = NSURL(string: "http://www.myurl.com/Token")
let request = NSMutableURLRequest(URL: url!);
request.HTTPMethod = "POST"
request.HTTPBody = data
request.addValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
request.addValue(base64LoginString, forHTTPHeaderField: "Authorization")
request.addValue("application/json", forHTTPHeaderField: "Accept")
request.setValue(postLength as String, forHTTPHeaderField: "Content-Length")
let task = NSURLSession.sharedSession().dataTaskWithRequest(request) {data, response, error in
if error != nil {
println("error = \(error)")
return
}
//print out response object
println("******* response = \(response)")
//print out response body // THIS LINE THROWS STATUS CODE 400 ERROR
let responseString = NSString(data: data, encoding: NSUTF8StringEncoding)
println("******* response data = \(responseString)")
var err: NSError?
var json = NSJSONSerialization.JSONObjectWithData(data, options: .MutableContainers, error: &err) as? NSDictionary
if let parseJSON = json {
var token = parseJSON["access_token"] as? String
println("token: \(token)")
}
}
task.resume()
}
This is the error
******* response = <NSHTTPURLResponse: 0x7ff1eb4496d0> { URL: https://www.myurl.com/Token } { status code: 400, headers {
"Cache-Control" = "no-cache";
"Content-Length" = 34;
"Content-Type" = "application/json;charset=UTF-8";
Date = "Mon, 10 Aug 2015 20:16:14 GMT";
Expires = "-1";
Pragma = "no-cache";
"X-Powered-By" = "ASP.NET";
} }

Answer 1

Your error seems to be incorrect usage of basic auth format. It should be like this:
Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
where
QWxhZGRpbjpvcGVuIHNlc2FtZQ==
is username:password in base64
So in your case it is like this :
let postString = userName.text + ":" + password.text ;
let data: NSData = postString.dataUsingEncoding(NSUTF8StringEncoding)!
let base64LoginString = data.base64EncodedStringWithOptions(nil)
let postLength=NSString(format: "%ld", data.length)
let url = NSURL(string: "http://www.myurl.com/Token")
let request = NSMutableURLRequest(URL: url!);
request.HTTPMethod = "POST"
request.HTTPBody = ""
request.addValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
request.addValue("Basic " + base64LoginString, forHTTPHeaderField: "Authorization")
request.addValue("application/json", forHTTPHeaderField: "Accept")
request.setValue("0", forHTTPHeaderField: "Content-Length")
btw it would be a lot easier to find your error if you provide your api url

Answer 2

The error code 400 says that the server doesn't understand for request, maybe the request is malformed. This is very likely a client side issue. However, I've written a simple python http server, and used the code above (with only change to the URL entry point), everything works. I strongly suggest that you should check the API documentation on the backend and find out why your backend server doesn't recognize your request. Your client side code seems correct.
Try this on your own:
Create myserver.py, and add the following lines to it:
from flask import Flask, request
app = Flask(__name__)
#app.route('/Token', methods=['POST'])
def hello_world():
print(request.form)
return 'Hello World!'
if __name__ == '__main__':
app.run()
Run this python script from terminal, and change http://www.myurl.com to http://127.0.0.1:5000, you'll see that the request gets through, and the server can correctly parse your username password, etc.
It's always a good idea to try to setup your own local web server to mock the backend during debugging/development according to backend API specification.

Answer 3

try this one
//first make json object.you can use your object for this one.
let JSONObject: [String : AnyObject] = [
"DeviceHash" : UUIDValue,
"DeviceName" : deviceNameValue!,
"SerialKey": serialKeyValue!,
]
if NSJSONSerialization.isValidJSONObject(JSONObject) {
var request: NSMutableURLRequest = NSMutableURLRequest()
let url = "Your Url"
var err: NSError?
request.URL = NSURL(string: url)
request.HTTPMethod = "POST"
request.cachePolicy = NSURLRequestCachePolicy.ReloadIgnoringLocalCacheData
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
do {
request.HTTPBody = try NSJSONSerialization.dataWithJSONObject(JSONObject, options: NSJSONWritingOptions())
print(JSONObject)
} catch {
print("bad things happened")
}
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue()) {(response, data, error) -> Void in
let httpResponse = response as! NSHTTPURLResponse
if error != nil {
print("error")
}else {
print(response)
}
}
}