LoadData - Read, Write, Download File in Unity3D

using UnityEngine;
using System.Collections;
using System;
using System.IO;

public class LoadData : MonoBehaviour {

    // Use this for initialization
    void Start () {
        WriteFile ("mao.txt");
        // get
//      string url = "http://example.com/script.php?var1=value2&var2=value2";
//      WWW www = new WWW(url);
//      StartCoroutine(WaitForRequest(www));


        // post
//      string url = "http://example.com/script.php";
//      WWWForm form = new WWWForm();
//      form.AddField("var1", "value1");
//      form.AddField("var2", "value2");
//      WWW www = new WWW(url, form);
//      StartCoroutine(WaitForRequest(www));

        string url = "http://data.crackgame.net/test/DataPetvenger/levels.xml";
        //"http://data.crackgame.net/test/DataPetvenger/DataGame";
        WWW www = new WWW(url);
        //StartCoroutine(WaitForRequest(www));

        StartCoroutine (TestDownload());
    }

    private IEnumerator TestDownload()
    {
        string progress = "";
        WWW www = new WWW("http://data.crackgame.net/test/DataPetvenger/levels.xml");
        //yield return www;

        while (!www.isDone) {
            progress = "downloaded " + (www.progress*100).ToString() + "%...";
            //Debug.Log("progress " + progress);
            yield return null;
        }

        string fullPath = Application.persistentDataPath + "/levels.xml";
        File.WriteAllBytes (fullPath, www.bytes);

        //progress = "downloaded, unzipping...";

    }

    IEnumerator WaitForRequest(WWW www)
    {
        yield return www;
        // check for errors
        if (www.error == null)
        {
            Debug.Log("WWW Ok!: " + www.data);
        } else {
            Debug.Log("WWW Error: "+ www.error);
        }
    }

    void WriteFile(string fileName){
        string urlFile = Application.persistentDataPath + "/" +fileName;
        if (File.Exists(urlFile))
        {
            Debug.Log(urlFile+" already exists.");
            return;
        }
        Debug.Log ("Dang ghi file");
        StreamWriter sr = File.CreateText(urlFile);
        sr.WriteLine ("Thieu Mao");
        sr.WriteLine ("Mot Mao");
        sr.Close();
    }



    void ReadFile(string file){

        if(File.Exists(file)){
            var sr = File.OpenText(file);
            var line = sr.ReadLine();
            while(line != null){
                Debug.Log(line); // prints each line of the file
                line = sr.ReadLine();
            }
        } else {
            Debug.Log("Could not Open the file: " + file + " for reading.");
            return;
        }
    }

}