Help Change Color of Object on Collide

Hi All,

I have been trying to figure out the script so that when my player Obj collides with platform Obj, the platform changes color instantly and stays that color, i have the below so far, any help please?

Many Thanks.

using UnityEngine;
using System.Collections;

public class Colour : MonoBehaviour {

void OncollisionEnter2D(Collision2D col)
{
	if(col.gameObject.tag == "Platform")
	{
		renderer.material.color = Color.cyan;
	}
}

}

Try this:

public class Colour : MonoBehaviour 
{
     void OncollisionEnter2D(Collision2D col)
    {
        if(col.gameObject.tag == "Platform")
        {
            col.gameObject.GetComponent<Renderer>().material.color = Color.cyan;
        }
    }
}