How to call funtion method in UIButton by Script

Hi all, I want to load list of items dynamic from UIScrollView by NGUI. I have defined a prefab.

In a prefab contains:

1. UIButton

2. UILable display name

I have use this tutorial create list of items dynamic by UIScrollView:

https://www.youtube.com/watch?v=AjzJrbiTJgE

And my code here:

     public GameObject scrollView;
     public GameObject itemPref;
     void Start() {
         for (int i = 0; i < 5; i++) {
             GameObject item = NGUITools.AddChild(scrollView, itemPref);    
             item.name = "Item" + i;
         }
         scrollView.transform.parent.GetComponent<UIScrollView> ().ResetPosition ();
         scrollView.GetComponent<UIGrid> ().Reposition ();
 
         GameObject gm = GameObject.Find ("Item0");
         UIButton btn = gm.GetComponentInChildren<UIButton> ();
         Debug.Log ("btn Name: " + btn.name);
     }

I have get a UIButton from prefab. How to call function click when i touched on UIButton "btn" by Script?

 GameObject gm = GameObject.Find ("Item0");
 UIButton btn = gm.GetComponentInChildren<UIButton> ();
 Debug.Log ("btn Name: " + btn.name);

Please help me resolve this issue. Thanks all!