下面介绍一个下载一个网络资源保存到本地的例子，正好是现在项目中的需求。

using UnityEngine; using System.Collections; using System.IO;  public class Download : MonoBehaviour  { 	public string url = "http://ww3.sinaimg.cn/large/80dfe250jw1dle1r2v4t9j.jpg"; 	public GUIText Test; 	WWW www; 	Color Alpha; 	bool Appear = false; 	int a = 0; 	 	IEnumerator Start()  	{ 		www = new WWW(url); 		//定义www为WWW类型并且等于所下载下来的WWW中内容。 		yield return www; 		//返回所下载的www的值 		renderer.material.shader = Shader.Find("Transparent/Diffuse"); 		renderer.material.mainTexture = www.texture; 		 		Texture2D newTexture = www.texture; 		byte[] pngData = newTexture.EncodeToPNG(); 		try 		{ 			if (Application.platform == RuntimePlatform.Android) 			{ 				File.WriteAllBytes(Application.persistentDataPath + "/ICO.png", pngData); 				 			} 			else 			{ 				//File.WriteAllBytes(Application.dataPath + "/download/ICO.png", pngData); 				File.WriteAllBytes(Application.dataPath + "/ICO.png", pngData); 			} 		} 		catch(IOException e) 		{ 			print(e); 		} 		 		Alpha = renderer.material.color; 		Alpha.a = 0; 		Appear = true; 		renderer.enabled = true; 		renderer.material.color = Alpha; 		//将下载下来的WWW中的图片赋予到默认物体的材质上进行渲染出来 	} 	 	void Update() 	{ 		Test.text = "DownLoad: " + www.progress; 		if(www.progress == 1 && Appear)	 		{ 			a++; 			Alpha = renderer.material.color; 			Alpha.a += 0.01F; 			renderer.material.color = Alpha; 		} 		 		if(Input.GetKey(KeyCode.Escape))            {                Application.Quit();            }    	} 	 	void OnGUI()         {            if(GUI.Button(new Rect(Screen.width-120,Screen.height-40,120,30),"Click to XIAOWEI!"))             {                Application.OpenURL("http://blog.csdn.net/dingxiaowei2013");            }        }    }

运行后会发现程序中本来没有ICO.png的，后来就多出来了，这就达到预想的效果！