错误代码如下：
Assets/NGUI/Examples/Scripts/Other/ShaderQuality.cs(18,48): error CS0117: `UnityEngine.QualitySettings' does not contain a definition for `GetQualityLevel'
范例的场景也打不开，求高手，怎么解决啊？
出错的脚本ShaderQuality，代码如下：
using UnityEngine;
/// <summary>
/// Change the shader level-of-detail to match the quality settings.
/// </summary>
[ExecuteInEditMode]
[AddComponentMenu("NGUI/Examples/Shader Quality")]
public class ShaderQuality : MonoBehaviour
{
int mCurrent = 600;
void Update ()
{
#if UNITY_3_4
int current = ((int)QualitySettings.currentLevel + 1) * 100;
#else
int current = (QualitySettings.GetQualityLevel() + 1) * 100;
#endif
if (mCurrent != current)
{
mCurrent = current;
Shader.globalMaximumLOD = mCurrent;
}
}
}