im trying to do an immortal state when my player take damage

Questions & Answers
1

im trying to do an immortal state that when my player takes damage but my TakeDamage method not working

    [SerializeField]
private float immortalTime;
private bool immortal = false;

public IEnumerator TakeDamage(int dmg)
{
	if (!immortal) 
	{
		currentPlayerHealth -= dmg;
		graphics.GetComponent<Animator>().SetTrigger("damage");
		immortal = true;
		StartCoroutine (IndicateImmortal());
		yield return new WaitForSeconds (immortalTime);
		immortal = false;
	}	
}
private IEnumerator IndicateImmortal()
{
	while (immortal) 
	{
		spriteRenderer.enabled = false;
		yield return new WaitForSeconds (.1f);
		spriteRenderer.enabled = true;
		yield return new WaitForSeconds (.1f);
	}
}

then here is my Damage source script

using UnityEngine;
using System.Collections;

public class Spike : MonoBehaviour {

//[SerializeField]
public int damage;

void OnTriggerEnter2D(Collider2D other)
{
	if (other.tag == "Player") 
	{
		other.GetComponent<Player> ().TakeDamage (damage);
	}	
}

}

2

Coroutines needs to be started with StartCoroutine. You’re calling TakeDamage as if it was a normal function. Try this:

public void TakeDamage(int dmg)
{
    StartCoroutine(TakeDamage_Coroutine(dmg));
}

 IEnumerator TakeDamage_Coroutine(int dmg)
 {
     if (!immortal) 
     {
         currentPlayerHealth -= dmg;
         graphics.GetComponent<Animator>().SetTrigger("damage");
         immortal = true;
         StartCoroutine (IndicateImmortal());
         yield return new WaitForSeconds (immortalTime);
         immortal = false;
     }    
 }
3

TakeDamage is a coroutine, which means you cannot start it like you attempted here in your code:

void OnTriggerEnter2D(Collider2D other)
 {
     if (other.tag == "Player") 
     {
         other.GetComponent<Player> ().TakeDamage (damage);
     }    
 }

Instead you need to use the StartCoroutine like you did when TakeDamage() starts the IndicateImmortal() coroutine. You could also turn TakeDamage into a regular method, and have it start the coroutine. This is typically better, as the object that starts the coroutine also manages it. An example of that would be this:

public void TakeDamage(float damage)
{
       StartCoroutine(TakeDamageCoroutine());
}

private IEnumerator TakeDamageCoroutine()
{
       if (!immortal) 
      {
           currentPlayerHealth -= dmg;
           graphics.GetComponent<Animator>().SetTrigger("damage");
           immortal = true;
           StartCoroutine (IndicateImmortal());
           yield return new WaitForSeconds (immortalTime);
           immortal = false;
     }    
}

Then in the other script you call:

 public int damage;
 void OnTriggerEnter2D(Collider2D other)
 {
     if (other.tag == "Player") 
     {
         other.GetComponent<Player> ().TakeDamage (damage);
     }    
 }