Button onClick Listener in unity C#
using UnityEngine;
using UnityEngine.UI;
using System.Collections;public class ClickExample : MonoBehaviour
{
    public Button yourButton;    void Start()
    {
        Button btn = yourButton.GetComponent<Button>();
        btn.onClick.AddListener(TaskOnClick);
    }    void TaskOnClick()
    {
        Debug.Log("You have clicked the button!");
    }
}