Unity5.x不在允許通過string的格式給材質新增shader，必須通過shaderAssets，否則警告：

UnityEngine.Material.Material(string) is obsolete:'Creating materials from shader source string is no longer supported. Use Shader assets instead.'

        具體操作方法：

1、新增一個Shader，放入工程中：

Shader "UI/Default Grey" {  
 Properties {  
  _MainTex ("Base (RGB)", 2D) = "white" {}  
  _Specular ("Specular", Range(1.0, 500.0)) = 250.0  
 }  
...
 

Material mat = new Material(Shader.Find("UI/Default Grey"));
(img.GetComponent<Renderer>() as Renderer).material = mat;