DragAndDrop

// DragTest-2D 参照
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;
//CameraのProjectionはOrthographicに。

[RequireComponent(typeof(Image))]
public class DragObj : MonoBehaviour, IDragHandler, IBeginDragHandler, IEndDragHandler
{
    private Vector2 prevPos;
    private Image image;
    void Start()
    {
     image = this.GetComponent();
    }
    public void OnBeginDrag(PointerEventData eventData)
    {
        // ドラッグ前の位置を記憶しておく
        prevPos = transform.position;
    }
    public void OnDrag(PointerEventData eventData)
    {
        Vector3 TargetPos = Camera.main.ScreenToWorldPoint(eventData.position);
        TargetPos.z = 0;
        transform.position = TargetPos;
    }
    public void OnEndDrag(PointerEventData eventData)
    {
        bool flg = true;
        var raycastResults = new List();
        EventSystem.current.RaycastAll(eventData, raycastResults);
        foreach (var hit in raycastResults)
        {
           if (hit.gameObject.CompareTag("image"))
         {
            transform.position = hit.gameObject.transform.position;
              image.enabled = false;
              //   Destroy(image);
            }
        }
        if (flg)
        {
            transform.position = prevPos;
        }
    }
}