Simple Looping drag and drop game

Question

hi, I'm trying to do a simple drag and drop game for my nephew (maybe can publish it in playstore). Because of that I will work with so many items I don't want to write code for each of them. I want to make a loop to find them by their index number and move to it's place with the same index number. this is the code I came up with. but it's not working and giving me theese errors; IndexOutOfRangeException: Index was outside the bounds of the array. MouseDrag.Start () (at Assets/MouseDrag.cs:22) Assets\DragAndDrop.cs(10,25): warning CS0649: Field 'DragAndDrop.initialPosition' is never assigned to, and will always have its default value null

I'm sure there are many other errors that I don't know. is there any body here have an idea or could show me how to do it. I'm desperately need any kind of help now.

Here is the code I tried to write:

`public class MouseDrag : MonoBehaviour { public GameObject[] objects;

 public Transform[] objectPlace;
 public List <Vector2> initialPosition = new List<Vector2>();
 private Vector2 mousePosition;
 private float deltaX, deltaY;
 int i = 0;
 public static bool locked;

 private void Start()
 {     
     for(int i=0; i< objects.Length; i++) 
     
           initialPosition.Add(new Vector2());
           initialPosition[i] = objects[i].transform.position;
         
           
     
     
 }
 
    void OnMouseDown()
 {    
     
         metod(i);
         
         
         deltaX = Camera.main.ScreenToWorldPoint(Input.mousePosition).x - transform.position.x;
         deltaY = Camera.main.ScreenToWorldPoint(Input.mousePosition).y - transform.position.y;
     
     
 
 }
       void OnMouseDrag() {
             if(!locked){
             mousePosition = Camera.main.ScreenToWorldPoint(Input.mousePosition);
              transform.position = new Vector2(mousePosition.x - deltaX, mousePosition.y - deltaY);
             }
         }
          void OnMouseUp()
 {
         if(Mathf.Abs(transform.position.x - objectPlace[i].position.x) <= 0.5f &&
             Mathf.Abs(transform.position.y - objectPlace[i].position.y)<= 0.5f)
             {
                 transform.position = new Vector2(objectPlace[i].position.x, objectPlace[i].position.y);
                 locked = true;
                 
             }
     }

     public int metod(int i)
     {
             for(int p = 0; p < objects.Length; p++)
     if ( !locked)
     {    
         RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.mousePosition), Vector2.zero);
         
         if (hit.collider.gameObject == objects[p].gameObject){Debug.Log("index number is: " + objects[p].transform.position.ToString());}
         p = i;}
         return i;
     }

}

Answer 1

2 things wrong here on a wuick overview:

delete the line initialposition.add and ad directly the position = initialPosition.Add(objects[i].transform.position);

metod i is wrong, you call it in the update section with i. is never asigned or a valid int. delet int i in metod because its unecessary, instead return p directly

Edit, Final working Script:

 using UnityEngine;
 using System.Collections.Generic;
 public class MouseDrag : MonoBehaviour{
 
         public float distanceToEndPos = 1;
         public List<GameObject> objects = new List<GameObject>();
         public List<Vector2> initialPosition = new List<Vector2>();
         public List<Vector2> desiredPosition = new List<Vector2>();
         Vector3 mousePos;
         Transform curObj;
         int curIndex;
         bool isDraging = false;
         
         void Start(){
                 objects.AddRange(GameObject.FindGameObjectsWithTag("DragAndDropObjects"));
                 foreach(GameObject g in objects){
                     initialPosition.Add(g.transform.position);
                 }
                 GameObject[] desObj = GameObject.FindGameObjectsWithTag("DragAndDropEndPos");
                 foreach(GameObject g in desObj){
                     desiredPosition.Add(g.transform.position);
                 }
         }
         void Update(){
             mousePos = GetMousePos();
             if(!isDraging){
                 GetRayCast();
             }
             if(isDraging){
                 DragAndDrop();
             }
         }
         public void GetRayCast(){
             RaycastHit2D hit = Physics2D.Raycast(new Vector2(mousePos.x,mousePos.y),Vector2.one);
                 if(hit.collider != null && Input.GetMouseButtonDown(0) && hit.transform.tag == "DragAndDropObjects"){
                     for(int i = 0; i<objects.Count;i++){
                         if(hit.collider != null && Input.GetMouseButtonDown(0) && hit.transform.gameObject == objects[i]){
                             curIndex = i;
                             curObj = objects[i].transform;
                             isDraging = true;
                         }
                     }
                 
             }
         }
         
         public Vector3 GetMousePos(){
             Vector3 mp = new Vector3();
             mp = Camera.main.ScreenToWorldPoint(Input.mousePosition);
             return new Vector3(mp.x,mp.y,0);
         }
         public void DragAndDrop(){
             if(curObj != null){
                 if(Input.GetMouseButton(0)){
                     curObj.position = mousePos;
                     
                 }
                 if(Input.GetMouseButtonUp(0)){
                     if(Vector2.Distance(mousePos,desiredPosition[curIndex]) <= distanceToEndPos){
                         curObj.position = desiredPosition[curIndex];
                         curObj = null;
                         isDraging = false;
                     }else{
                         curObj.position = initialPosition[curIndex];
                         curObj = null;
                         isDraging = false;
                     }
                 }
             }
         }
     }

Simple Looping drag and drop game

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