ENEMY HEALTH BAR

hey guys i'm having a problem, i want to my enemy health bar show up when my player is close to the enemy but i don't know how to do it please can someone help me?

this is the enemy lifebar code:

using UnityEngine; using System.Collections;

public class EnemyHealth : MonoBehaviour { public int MaxHealth = 100; public int CurHealth = 100; //public bool barradevida = false; //public int maxDistance; //public int minDistance; public Transform target; private Transform myTransform; public Transform BarraInterface;

 public float HealthBarLenght;


 // Use this for initialization
 void Start ()
 {
     //GameObject go = GameObject.FindGameObjectWithTag("Player");
     
     //target = go.transform;
     
     //maxDistance = 2;
     //minDistance = 7;
 
     HealthBarLenght = Screen.width / 4;
 }

 // Update is called once per frame
 void Update ()
 {
     
 
     
     
     
     AdjustCurrentHealth (0);
     
 }

 public void OnGUI ()
 {
     
     
     
     GUI.Box (new Rect (900, 20, HealthBarLenght, 20), CurHealth + "/" + MaxHealth);
     
     
 }

 public void AdjustCurrentHealth (int adj)
 {
     CurHealth += adj;
     
     if (CurHealth < 0)
         CurHealth = 0;
     
     //if(CurHealth == 0)
     //GameObject.Destroy(gameObject);
     
     
     
     //if(CurHealth == 0)
     //GameObject.Destroy(GameObject.FindWithTag == "Enemy");
     
     if (CurHealth <= 0) {
         Destroy (gameObject);
     }
     
     
     if (CurHealth > MaxHealth)
         CurHealth = MaxHealth;
     
     if (MaxHealth < 1)
         MaxHealth = 1;
     
     
     HealthBarLenght = (Screen.width / 4) * (CurHealth / (float)MaxHealth);
     
     //GameObject.Destroy(GameObject.FindWithTag == "Enemy");
     
 }
 
 
 
 

}

AND this is my enemy AI code

using UnityEngine; using System.Collections;

public class EnemyAI : MonoBehaviour { public Transform target; public int moveSpeed; public int rotationSpeed; public int maxDistance; public int minDistance;

 private Transform myTransform;
 // isso serve para deixar as coisas mais rapidas, espero descobrir mais depois
 void Awake() {
     myTransform = transform;
 }
 
 // Use this for initialization
 void Start () {
     
     
        
     GameObject go = GameObject.FindGameObjectWithTag("Player");
     
     target = go.transform;
     
     maxDistance = 2;
     minDistance = 7;
     
     
 }
 
 // Update is called once per frame
 void Update () 
 {
 
     if(Vector3.Distance(target.position,  myTransform.position) <= minDistance)
     {
     
     Debug.DrawLine(target.transform.position, myTransform.position, Color.yellow);
 
     // olhar para o alvo
     myTransform.rotation = Quaternion.Slerp(myTransform.rotation, Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed * Time.deltaTime);
     
     if(Vector3.Distance(target.position,  myTransform.position) > maxDistance) {
         
         
     
     //move até o alvo
     
         
          myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
         
         }
         
     }
 }

}