How to make HTTP Post request with JSON body in Swift

Question

Try this,

// prepare json data
let json: [String: Any] = ["title": "ABC",
                           "dict": ["1":"First", "2":"Second"]]

let jsonData = try? JSONSerialization.data(withJSONObject: json)

// create post request
let url = URL(string: "http://httpbin.org/post")!
var request = URLRequest(url: url)
request.httpMethod = "POST"

// insert json data to the request
request.httpBody = jsonData

let task = URLSession.shared.dataTask(with: request) { data, response, error in
    guard let data = data, error == nil else {
        print(error?.localizedDescription ?? "No data")
        return
    }
    let responseJSON = try? JSONSerialization.jsonObject(with: data, options: [])
    if let responseJSON = responseJSON as? [String: Any] {
        print(responseJSON)
    }
}

task.resume()

or try a convenient way Alamofire

Swift 4 and 5

HTTP POST request using URLSession API in Swift 4

func postRequest(username: String, password: String, completion: @escaping ([String: Any]?, Error?) -> Void) {

    //declare parameter as a dictionary which contains string as key and value combination.
    let parameters = ["name": username, "password": password]

    //create the url with NSURL
    let url = URL(string: "https://www.myserver.com/api/login")!

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

    //now create the Request 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 data object and set it as request body
    } catch let error {
        print(error.localizedDescription)
        completion(nil, error)
    }

    //HTTP Headers
    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, completionHandler: { data, response, error in

        guard error == nil else {
            completion(nil, error)
            return
        }

        guard let data = data else {
            completion(nil, NSError(domain: "dataNilError", code: -100001, userInfo: nil))
            return
        }

        do {
            //create json object from data
            guard let json = try JSONSerialization.jsonObject(with: data, options: .mutableContainers) as? [String: Any] else {
                completion(nil, NSError(domain: "invalidJSONTypeError", code: -100009, userInfo: nil))
                return
            }
            print(json)
            completion(json, nil)
        } catch let error {
            print(error.localizedDescription)
            completion(nil, error)
        }
    })

    task.resume()
}

@objc func submitAction(_ sender: UIButton) {
    //call postRequest with username and password parameters
    postRequest(username: "username", password: "password") { (result, error) in
    if let result = result {
        print("success: \(result)")
    } else if let error = error {
        print("error: \(error.localizedDescription)")
    }
}

Using Alamofire:

let parameters = ["name": "username", "password": "password123"]
Alamofire.request("https://www.myserver.com/api/login", method: .post, parameters: parameters, encoding: URLEncoding.httpBody)

HTTP Post in Swift capturing the errors

let json = [ Activity.KEY_IDSUBJECT : activity.idSubject, Activity.KEY_RECORDMODE : "3", Activity.KEY_LOCATION_LONGITUDE : "0",Activity.KEY_LOCATION_LATITUDE : "0", Activity.KEY_CHECKIN : String(activity.dateCheckIn), Activity.KEY_CHECKOUT : String(activity.dateCheckOut) ]

do {
    let jsonData = try NSJSONSerialization.dataWithJSONObject(json, options: .PrettyPrinted)

    // create post request
    let url = NSURL(string: "https://...appspot.com/_ah/api/activityendpoint/v1/activity")!
    let request = NSMutableURLRequest(URL: url)
    request.HTTPMethod = "POST"

    // insert json data to the request
    request.setValue("application/json; charset=utf-8", forHTTPHeaderField: "Content-Type")
    request.HTTPBody = jsonData


    let task = NSURLSession.sharedSession().dataTaskWithRequest(request){ data, response, error in
        if error != nil{
            print("Error -> \(error)")
            return
        }

        do {
            let result = try NSJSONSerialization.JSONObjectWithData(data!, options: []) as? [String:AnyObject]

            print("Result -> \(result)")

        } catch {
            print("Error -> \(error)")
        }
    }

    task.resume()
    return task
} catch {
    print(error)
}

SWIFT 5 People Here :

let json: [String: Any] = ["key": "value"]

        let jsonData = try? JSONSerialization.data(withJSONObject: json)

        // create post request
        let url = URL(string: "http://localhost:1337/postrequest/addData")! //PUT Your URL
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("\(String(describing: jsonData?.count))", forHTTPHeaderField: "Content-Length")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        // insert json data to the request
        request.httpBody = jsonData

        let task = URLSession.shared.dataTask(with: request) { data, response, error in
            guard let data = data, error == nil else {
                print(error?.localizedDescription ?? "No data")
                return
            }
            let responseJSON = try? JSONSerialization.jsonObject(with: data, options: [])
            if let responseJSON = responseJSON as? [String: Any] {
                print(responseJSON) //Code after Successfull POST Request
            }
        }

        task.resume()

The following Swift 5 Playground code shows a possible way to solve your problem using JSONSerialization and URLSession:

import UIKit
import PlaygroundSupport

PlaygroundPage.current.needsIndefiniteExecution = true

let url = URL(string: "http://localhost:8080/new")!
let jsonDict = ["firstName": "Jane", "lastName": "Doe"]
let jsonData = try! JSONSerialization.data(withJSONObject: jsonDict, options: [])

var request = URLRequest(url: url)
request.httpMethod = "post"
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
request.httpBody = jsonData

let task = URLSession.shared.dataTask(with: request) { (data, response, error) in
    if let error = error {
        print("error:", error)
        return
    }

    do {
        guard let data = data else { return }
        guard let json = try JSONSerialization.jsonObject(with: data, options: []) as? [String: AnyObject] else { return }
        print("json:", json)
    } catch {
        print("error:", error)
    }
}

task.resume()