碰撞阻止敌人攻击-Unity3D

我有一个简单的游戏，玩家保护中心基地不攻击敌人。目前，当玩家触碰基地时，所有敌人都停止攻击。攻击由Enemy脚本中的协同例程处理。我已经在下面发布了敌人和基地的脚本。敌方脚本

using UnityEngine;
using System.Collections;
public class Enemy : MonoBehaviour {
public static float Damage = 10.0f;
public float Health = 20.0f;
public Transform target;
public float Speed;
public bool isAttacking = false;
//If the player collides with the enemy
void OnTriggerEnter2D(Collider2D col)
{
    if(col.gameObject.tag == "Player")
    {
        Debug.Log("Player hits enemy");
        Health -= PlayerController.Damage;
        Debug.Log("Enemy health at: " + Health);
    }
}

// Use this for initialization
void Start () {
}
// Update is called once per frame
void Update () {
    //Destroy the enemy if it's health reaches 0
        if(Health <= 0){
            isAttacking = false;
            Debug.Log ("Is attacking: " + isAttacking);
            Destroy(this.gameObject);
            Debug.Log ("Enemy Destroyed!");
        }
    //Constantly move the enemy towards the centre of the gamespace (where the base is)
    float step = Speed * Time.deltaTime;
    transform.position = Vector3.MoveTowards(transform.position, target.position, step);
}
}

基本脚本

using UnityEngine;
using System.Collections;
public class Base : MonoBehaviour {
public float Health = 100f;
public float AttackSpeed = 2f;
//VOID AWAKE - START . contains getcomponent code
public Enemy enemy;
void awake(){
    enemy = GetComponent<Enemy>();
}
//VOID AWAKE - END
//If enemy touches the base 
void OnCollisionEnter2D(Collision2D col){
    Debug.Log ("Base touched");
    if(col.gameObject.tag == "Enemy" && Health > 0f){
        enemy.isAttacking = true;
        Debug.Log ("Enemy attacking base");
        StartCoroutine("enemyAttack");
    }
    else{
        enemy.isAttacking = false;
    }
}
//Coroutine that deals damage
public IEnumerator enemyAttack(){
    while(Health > 0f){
        if(enemy.isAttacking == true){
            yield return new WaitForSeconds(2f);
            Health -= Enemy.Damage;
            Debug.Log ("Base health at: " + Health);
        }else{
            yield break;
        }
    }
}
// Use this for initialization
void Start () {
}
// Update is called once per frame
void Update () {
    //Load Lose Screen when Base health reaches 0
    if (Health <= 0){
        Application.LoadLevel("Lose Screen");
    }
}
}