例子：获取一个TEXT组件

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class SilderText : MonoBehaviour 
{
public Slider slider;
Text mytext;

// Update is called once per frame
public void UpdateText () 
{
mytext = gameObject.GetComponent<Text>();
mytext.text = slider.value.ToString();
}
}

在头文件里必须加上 using UnityEngine.UI;  这样才能正确的获取的到

unity3d4.6UGUI之后获取UI组件的方法