A basic showing multipart/form-data implementation using swift.

multipart_formdata.swift

import UIKit
import Foundation

let image = UIImage(named: "example.jpg")
let imageData = image!.jpegData(compressionQuality: 0.75)
let date = Date()
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let dateString = dateFormatter.string(from: date)

let url = URL(string: "https://example.com/upload")!
var request = URLRequest(url: url)
request.httpMethod = "POST"

let boundary = "Boundary-\(UUID().uuidString)"
request.setValue("multipart/form-data; boundary=\(boundary)", forHTTPHeaderField: "Content-Type")

var data = Data()

data.append("\r\n--\(boundary)\r\n".data(using: .utf8)!)
data.append("Content-Disposition: form-data; name=\"image\"; filename=\"example.jpg\"\r\n".data(using: .utf8)!)
data.append("Content-Type: image/jpeg\r\n\r\n".data(using: .utf8)!)
data.append(imageData!)

data.append("\r\n--\(boundary)\r\n".data(using: .utf8)!)
data.append("Content-Disposition: form-data; name=\"name\"\r\n\r\n".data(using: .utf8)!)
data.append("example".data(using: .utf8)!)

data.append("\r\n--\(boundary)\r\n".data(using: .utf8)!)
data.append("Content-Disposition: form-data; name=\"date\"\r\n\r\n".data(using: .utf8)!)
data.append(dateString.data(using: .utf8)!)

data.append("\r\n--\(boundary)--\r\n".data(using: .utf8)!)

request.httpBody = data

let task = URLSession.shared.dataTask(with: request) { data, response, error in
    if let error = error {
        print("error: \(error)")
        return
    }
    if let response = response as? HTTPURLResponse {
        print("statusCode: \(response.statusCode)")
    }
    if let data = data, let dataString = String(data: data, encoding: .utf8) {
        print("data: \(dataString)")
    }
}
task.resume()