How to do object selection in Unity3d?

Question

C++ / C#

void OnTriggerStay(Collider col){
    if (col.gameObject.tag == "mob") 

    {
      GameObject target = GameObject.FindGameObjectWithTag ("mob");
      transform.LookAt(target.transform);
      }	
}

How to make it so that when the object exits the Trigger, the object starts looking for a new target
And does not look at the old
one If through OnTriigerExit
Then how to initialize an object that is already in target
So that when exiting Target = null;
And not when any object exits the Trigger
Thank you

Answer 1

OnTriggerExit2D?

Answer 2

There are also functions OnTriggerEnter and OnTriggerExit if I made a mistake with the names. The second is what you need.