if any game object with this tag ....

[system]

hi every one
I have some gameobjects named them lightcolor… and their tag is “LightColorBlue” … I want to say if any game objects with this tag get near this gameobject , do somthing… when I put public GameObject lightcolor and I put a GameObject in unity inspector it work perfect , but I don’t know how to say "if any gameobjects that have that tag get near… " I used below code but doesn’t work!!

using UnityEngine;
using System.Collections;

public class NoColorTree : MonoBehaviour {

    private GameObject lightcolor;

    void Start()
    {
        lightcolor = GameObject.FindWithTag("LightColorBlue");
    }
void Update() 
{
    if (Vector3.Distance(lightcolor.transform.position, transform.position) < 10)
    {
        renderer.material.color = Color.blue;
    }
   }
}

[Mortennobel]

I changed your code slightly so that it is the objects with the tag ‘LightColorBlue’ that will change color (in your code it was the object containing the script FindTestTag.
Also I added another color when the object was not found (maybe you don’t need this - but it makes it easy to see in a test-case).

The new modified script is:

using UnityEngine;
using System.Collections;

public class FindTestTag : MonoBehaviour {
	
	private GameObject[] lightcolors;
	
	// Use this for initialization
	void Start () {
		lightcolors = GameObject.FindGameObjectsWithTag("LightColorBlue");
	}
	
	// Update is called once per frame
	void Update () {
		foreach (GameObject  lightcolor in lightcolors){
			if (Vector3.Distance(lightcolor.transform.position, transform.position) < 10)
		    {
		        lightcolor.renderer.material.color = Color.blue;
		    } else {
				lightcolor.renderer.material.color = Color.red;
			}
		}
	}
}