HTTP Request in Swift with POST method

Question

In Swift 3 and later you can:

let url = URL(string: "http://www.thisismylink.com/postName.php")!
var request = URLRequest(url: url)
request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
request.httpMethod = "POST"
let parameters: [String: Any] = [
    "id": 13,
    "name": "Jack & Jill"
]
request.httpBody = parameters.percentEncoded()

let task = URLSession.shared.dataTask(with: request) { data, response, error in
    guard let data = data, 
        let response = response as? HTTPURLResponse, 
        error == nil else {                                              // check for fundamental networking error
        print("error", error ?? "Unknown error")
        return
    }

    guard (200 ... 299) ~= response.statusCode else {                    // check for http errors
        print("statusCode should be 2xx, but is \(response.statusCode)")
        print("response = \(response)")
        return
    }

    let responseString = String(data: data, encoding: .utf8)
    print("responseString = \(responseString)")
}

task.resume()

Where:

extension Dictionary {
    func percentEncoded() -> Data? {
        return map { key, value in
            let escapedKey = "\(key)".addingPercentEncoding(withAllowedCharacters: .urlQueryValueAllowed) ?? ""
            let escapedValue = "\(value)".addingPercentEncoding(withAllowedCharacters: .urlQueryValueAllowed) ?? ""
            return escapedKey + "=" + escapedValue
        }
        .joined(separator: "&")
        .data(using: .utf8)
    }
}

extension CharacterSet { 
    static let urlQueryValueAllowed: CharacterSet = {
        let generalDelimitersToEncode = ":#[]@" // does not include "?" or "/" due to RFC 3986 - Section 3.4
        let subDelimitersToEncode = "!$&'()*+,;="

        var allowed = CharacterSet.urlQueryAllowed
        allowed.remove(charactersIn: "\(generalDelimitersToEncode)\(subDelimitersToEncode)")
        return allowed
    }()
}

This checks for both fundamental networking errors as well as high-level HTTP errors. This also properly percent escapes the parameters of the query.

Note, I used a name of Jack & Jill, to illustrate the proper x-www-form-urlencoded result of name=Jack%20%26%20Jill, which is “percent encoded” (i.e. the space is replaced with %20 and the & in the value is replaced with %26).

---

See previous revision of this answer for Swift 2 rendition.

Swift 4 and above

@IBAction func submitAction(sender: UIButton) {

    //declare parameter as a dictionary which contains string as key and value combination. considering inputs are valid

    let parameters = ["id": 13, "name": "jack"]

    //create the url with URL
    let url = URL(string: "www.thisismylink.com/postName.php")! //change the url

    //create the session object
    let session = URLSession.shared

    //now create the URLRequest object using the url object
    var request = URLRequest(url: url)
    request.httpMethod = "POST" //set http method as POST

    do {
        request.httpBody = try JSONSerialization.data(withJSONObject: parameters, options: .prettyPrinted) // pass dictionary to nsdata object and set it as request body
    } catch let error {
        print(error.localizedDescription)
    }

    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
    request.addValue("application/json", forHTTPHeaderField: "Accept")

    //create dataTask using the session object to send data to the server
    let task = session.dataTask(with: request as URLRequest, completionHandler: { data, response, error in

        guard error == nil else {
            return
        }

        guard let data = data else {
            return
        }

        do {
            //create json object from data
            if let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: Any] {
                print(json)
                // handle json...
            }
        } catch let error {
            print(error.localizedDescription)
        }
    })
    task.resume()
}

For anyone looking for a clean way to encode a POST request in Swift 5.

You don’t need to deal with manually adding percent encoding. Use URLComponents to create a GET request URL. Then use query property of that URL to get properly percent escaped query string.

let url = URL(string: "https://example.com")!
var components = URLComponents(url: url, resolvingAgainstBaseURL: false)!

components.queryItems = [
    URLQueryItem(name: "key1", value: "NeedToEscape=And&"),
    URLQueryItem(name: "key2", value: "vålüé")
]

let query = components.url!.query

The query will be a properly escaped string:

key1=NeedToEscape%3DAnd%26&key2=v%C3%A5l%C3%BC%C3%A9

Now you can create a request and use the query as HTTPBody:

var request = URLRequest(url: url)
request.httpMethod = "POST"
request.httpBody = Data(query.utf8)

Now you can send the request.

Heres the method I used in my logging library: https://github.com/goktugyil/QorumLogs

This method fills html forms inside Google Forms.

    var url = NSURL(string: urlstring)

    var request = NSMutableURLRequest(URL: url!)
    request.HTTPMethod = "POST"
    request.setValue("application/x-www-form-urlencoded; charset=utf-8", forHTTPHeaderField: "Content-Type")
    request.HTTPBody = postData.dataUsingEncoding(NSUTF8StringEncoding)
    var connection = NSURLConnection(request: request, delegate: nil, startImmediately: true)

let session = URLSession.shared
        let url = "http://...."
        let request = NSMutableURLRequest(url: NSURL(string: url)! as URL)
        request.httpMethod = "POST"
        request.addValue("application/json", forHTTPHeaderField: "Content-Type")
        var params :[String: Any]?
        params = ["Some_ID" : "111", "REQUEST" : "SOME_API_NAME"]
        do{
            request.httpBody = try JSONSerialization.data(withJSONObject: params, options: JSONSerialization.WritingOptions())
            let task = session.dataTask(with: request as URLRequest as URLRequest, completionHandler: {(data, response, error) in
                if let response = response {
                    let nsHTTPResponse = response as! HTTPURLResponse
                    let statusCode = nsHTTPResponse.statusCode
                    print ("status code = \(statusCode)")
                }
                if let error = error {
                    print ("\(error)")
                }
                if let data = data {
                    do{
                        let jsonResponse = try JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions())
                        print ("data = \(jsonResponse)")
                    }catch _ {
                        print ("OOps not good JSON formatted response")
                    }
                }
            })
            task.resume()
        }catch _ {
            print ("Oops something happened buddy")
        }