Coroutine not working (Unity)

Question

I made this code because I needed an image to display a couple seconds after an enemy spawns, but for some reason I can't make it work.

There's no error in the console, but it doesn't display the image and I don't know what to do. Here's my script (it's attached to the enemy prefab)

 public class enemyAttack : MonoBehaviour {

 public float time = 5f;
 private IEnumerator coroutine;    
 public Image image; 
 private float t = 5f;

 void Start ()
 {
     //image.gameObject.SetActive (false);
     image.enabled = false;
     coroutine = nombredeCorutina (time, image); 
     StartCoroutine (coroutine);
 }

 private IEnumerator nombredeCorutina (float t, Image im)
 {

     image.enabled = true;
     //im.gameObject.SetActive (true);
     yield return new WaitForSeconds (t);

     coroutine = nombredeCorutina (time, im);
     StartCoroutine (coroutine);
 }
}

Answer 1

You need to edit your code something like this:

public float time = 5f;
private IEnumerator coroutine;
public Image image;
private float t = 5f;

void Start() {
    image.enabled = false;
}

private IEnumerator nombredeCorutina(float t, Image im) {
    yield return new WaitForSeconds(t);
    image.enabled = true;
}

public void EnemySpawn() {
    //call enemey spawn whenver you want. it will register coroutine and you image will be displayed after given seconds
    //enemyspawn logic
    StartCoroutine(nombredeCorutina(t,image));
}

Now you have to identify that when should you disable your image and when you want to spawn enemy.

Answer 2

Some of your code is redundant or actively incorrect. For instance, why set the cooroutine in private and redeclare it over and over when you can just call it as is?

I've reordered your code to work correctly for the specific purposes you need it, if you wish to make your code reusable (which you should) then you'd have to structure it differently.

public class enemyAttack : MonoBehaviour {

    public float time = 5;   
    public GameObject gameObjectHoldingImage; //Obviously too long a name, but helps explain. 

    void Start (){
        gameObjectHoldingImage.SetActive (false);
        StartCoroutine(nombredeCorutina (time));
    }

    private IEnumerator nombredeCorutina (float t){         
        gameObjectHoldingImage.SetActive(true);
        yield return new WaitForSeconds (t);
        //If you call this again (repeating) it is redundant as the game 
        //object/image is not re-set to false. 
        StartCoroutine (nombredeCorutina (t));
    }
}