EventSystem.IsPointerOverGameObject

Parameters

Description

Is the pointer with the given id over an EventSystem object?

function Update()
	{
		if(Input.GetMouseButtonDown(0))
		{
			if(!EventSystems.EventSystem.current.IsPointerOverGameObject())
			{
				Debug.Log("Did not Click on the UI");
			}
		}
	}

using UnityEngine;
using System.Collections;
using UnityEngine.EventSystems;

public class example : MonoBehaviour {

	void Update () 
	{
		// Check if the left mouse button was clicked
		if(Input.GetMouseButtonDown(0))
		{
			// Check if the mouse was clicked over a UI element
			if(!EventSystem.current.IsPointerOverGameObject())
			{
				Debug.Log("Did not Click on the UI");
			}
		}	
	}
}

Note on C# that they will need to add "using UnityEngine.EventSystems;" Note that with C# you will need to add "using UnityEngine.EventSystems;".