request.swift

import UIKit

let url = URL(string: "http://127.0.0.1:1234")!
var request = URLRequest(url: url)
request.setValue("application/json", forHTTPHeaderField: "Content-Type")
request.setValue("you-value-goes-here", forHTTPHeaderField: "X-API-KEY")


let task = URLSession.shared.dataTask(with: request) { data, _, error in
    if let data = data {
        print(data)
    } else if let error = error {
        print("Http failed: \(error)")
    }
}

task.resume()