Helper class for executing a HTTP request using c# in Unity v5 by calling one function and supplying a callback (very similarly to jQuery)

GeneralDirector.cs

using UnityEngine;
using System.Collections;

public class GeneralDirector : MonoBehaviour {
	static public HTTP http;

	public void Start () {
		http = this.gameObject.GetComponent<HTTP> ();
	}
}

HTTP.cs

using System; 
using UnityEngine;
using System.Collections; 
using System.Collections.Generic; 

public class HTTP : MonoBehaviour {

	public void New(string url, Action<string> callback, Dictionary<string, string> fields) {
		StartCoroutine(MakeRequest(url, callback, fields)); 
	}

	public void New(string url, Action<string> callback) {
		New(url, callback, null); 
	}

	private IEnumerator MakeRequest(string url, Action<string> callback, Dictionary<string, string> fields) {

		WWWForm data = new WWWForm ();
		
		if (fields != null) {
			foreach (var field in fields) {
				data.AddField (field.Key, field.Value);
			}
		}
		
		WWW www = new WWW(url, data);

		yield return www;
		Debug.Log ("Request sent!");
		callback.Invoke (www.text);
	}
}

Main.cs

using System; 
using UnityEngine;
using System.Collections; 
using System.Collections.Generic; 

public class Main : MonoBehaviour {		

  public void Start() {
    // BASIC GET REQUEST
    // Make HTTP request to the url and call the "callback" function when complete
    GeneralDirector.http.New ("http://mysite.com", callback);
  
    // BASIC POST REQUEST
  	Dictionary<string, string> fields = new Dictionary<string, string> ();
  	fields.Add ("name", "James");
  	fields.Add ("score", "100");
  	// Make HTTP request to url including "fields" as POST variables,
  	// once complete the "callback" function is invoked
  	GeneralDirector.http.New ("http://mysite.com", callback, fields);
  }
  
  public void callback(string result) {
    Debug.Log("Response: "+result);
  }
}