Function to set enum is not working right.

Hello, I have a script on a game object which changes sprites randomly on trigger. I also have another function sets the color of the object from an enum. The function is supposed to checks the sprite of the game object and based on that it will set the color of the game object. But this function has not been working properly and also interfering in the the changing of the sprite of the gameobject. and now the game object is set on the same color throughout the game. This is my code for the gameobject: public class PlayerController : MonoBehaviour {

     public Sprite[] playerSprites = new Sprite[4]; //sprites to be used by player game object
     //playerSprite[0] = Red, playerSprite[1] = Pink,                                                    //playerSprite[2] = Purple, playerSprite[3] = Blue
     public ObjectColor playerColor;
     public int spriteIndex; //Random number to access sprites.
     SpriteRenderer sr;
     Rigidbody2D rb;
     public float gameSpeed;
     // Use this for initialization
     void Start ()
     {
         sr = GetComponent <SpriteRenderer> ();
         rb = GetComponent <Rigidbody2D> ();
         SetOrChangeSprite ();
         Debug.Log (sr.sprite);
         Debug.Log (SetColor (playerColor));
     }
     
     void FixedUpdate ()
     {
         MovePlayer ();
     }
 
     //Set or change the sprites of the player game object at runtime
     public void SetOrChangeSprite ()
     {
         spriteIndex = Random.Range (0, 4);
         sr.sprite = playerSprites [spriteIndex];
     }
 
     //Set the color of the player game object to an enum type
     ObjectColor SetColor (ObjectColor color)
     {
         if (sr.sprite = playerSprites [0])
         {
             color = ObjectColor.Red;
         }
         else if (sr.sprite = playerSprites [1])
         {
             color = ObjectColor.Pinkish;
         }
         else if (sr.sprite = playerSprites [2])
         {
             color = ObjectColor.Purple;
         }
         else if (sr.sprite = playerSprites [3])
         {
             color = ObjectColor.Blue;
         }
 
         return color;
     }
 
     void MovePlayer ()
     {
         rb.velocity = (new Vector2 (rb.velocity.x, 1f)) * gameSpeed;
         //transform.position += Vector3.up * gameSpeed * Time.deltaTime;
     }
 }
 

I have been trying to solve this problem since morning coming up with different solutions but nothing seems to be working. Could someone help me figure out whats wrong. And why the function does not set the player color and also prevents the sprites from being random. But when I delete the set color function, everything works like it should