代码：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.EventSystems;
using UnityEngine.UI;public class DragCreate : MonoBehaviour 
{public GameObject Cube;public GameObject Place;/// <summary>/// 按下响应/// </summary>public void PointerDown(){OnBeginDrag();}/// <summary>/// 开始拖拽/// </summary>public void OnBeginDrag(){GameObject game = Instantiate(Cube);game.SetActive(true);generateGame = game;float distance = Camera.main.transform.InverseTransformPoint(Place.transform.position).z;generateGame.transform.position = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x,Input.mousePosition.y, distance));generateGame.transform.rotation = Place.transform.rotation;Place.SetActive(true);}private GameObject generateGame;/// <summary>/// 进行拖拽/// </summary>public void OnDrag(){float distance = Camera.main.transform.InverseTransformPoint(Place.transform.position).z;generateGame.transform.position = Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x,Input.mousePosition.y, distance));}/// <summary>/// 结束拖拽/// </summary>public void OnEndDrag(){if (generateGame.transform.position.x > Place.transform.position.x - 0.3f&& generateGame.transform.position.x < Place.transform.position.x + 0.3f&& generateGame.transform.position.y > Place.transform.position.y - 0.3f&& generateGame.transform.position.y < Place.transform.position.y + 0.3f) {Place.SetActive(false);generateGame.transform.position = Place.transform.position;}else{Place.SetActive(false);Destroy(generateGame);}}
}

脚本挂载和层级：