cache system for unity

WWWCache.cs

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

/// <summary>
/// WWW cache.
/// </summary>
public class WWWCache {
	
	static string strToBase64 (string str)
	{
		//Debug.Log(str);
		byte[] byt = System.Text.Encoding.UTF8.GetBytes (str);
		return Convert.ToBase64String (byt);
	}
	
	static string base64ToStr (string base64)
	{
		byte[] b = Convert.FromBase64String (base64);
		return System.Text.Encoding.UTF8.GetString (b);
	}
	
	public static string UrlToCachePath (string url)
	{
		return Application.persistentDataPath + "/" + strToBase64 (url);
	}
	
	public static bool HasCache (string url)
	{
		return File.Exists (UrlToCachePath (url));
	}
	
	/// <summary>
	/// Write to cache file
	/// </summary>
	/// <returns>
	/// is success
	/// </returns>
	/// <param name='url'>
	/// url
	/// </param>
	/// <param name='bytes'>
	/// data
	/// </param>
	public static bool WriteCache (string url, byte[] bytes)
	{
		//Debug.LogWarning("url:"+url);
		//Debug.Log("path:"+urlToCachePath(url));
		
		long freeSpace = DiskSpace.FreeSpece;
		if (freeSpace < -1) {
			freeSpace = Math.Abs (freeSpace);
		}
		if (freeSpace <= bytes.Length && freeSpace >= -1) {
			return false;
		}
		
		bool success = false;
		try {
			File.WriteAllBytes (UrlToCachePath (url), bytes);
			success = true;
		} catch {
			Debug.LogError ("file save error");
			success = false;
		} finally {
			
		}
		return success;		
	}
	
	
	/// <summary>
	/// Delete cached file
	/// </summary>
	/// <returns>
	/// is successed
	/// </returns>
	/// <param name='url'>
	/// cached file URL
	/// </param>
	public static bool DeleteCache (string url)
	{
		string path = UrlToCachePath (url);
		if (!File.Exists (path)) {
			return false;
		} else {
			try {
				File.Delete (path);
			} catch (Exception ex) {
				Debug.LogWarning (ex);
				return false;
			}
		}
		return true;
	}
	
	public static string CacheUrl(string url) {	
		string path = UrlToCachePath(url);
		//Debug.LogWarning(data_path +" : "+path);
		if(File.Exists(path)) {
			return "file://" + path;
		}
		return "";
	}
	
}