Unity 拖拽示例

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

public class MoveSiblingItem :MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler, IPointerEnterHandler
{
    /// <summary>
    /// 起始父节点
    /// </summary>
    private Transform originalSlot;
    /// <summary>
    /// 总列表
    /// </summary>
    private GameObject itemRoot;
    /// <summary>
    /// 自身
    /// </summary>
    private GameObject itemSelf;
    /// <summary>
    /// 画布
    /// </summary>
    private CanvasGroup itemCanvasGroup;
    private bool isDragging = false;    
    public string objectTag = null;
    private int frontIndex = 0;
    public int itemlevel;//等级

    private void Start()
    {
        itemCanvasGroup = this.GetComponent<CanvasGroup>();
        itemSelf = this.transform.gameObject;
        itemRoot = GameObject.Find("Content");
    }
    public void OnBeginDrag(PointerEventData eventData)
    {
        originalSlot = this.GetComponent<Transform>().parent;
        isDragging = true;
        itemCanvasGroup.blocksRaycasts = true;
        itemSelf.transform.SetParent(itemRoot.transform, false);
        frontIndex = itemSelf.transform.GetSiblingIndex();
        itemSelf.transform.SetAsLastSibling();
        itemCanvasGroup.alpha = 0.5f;
        RefreshContentSizeFitter();
    }
    public void OnDrag(PointerEventData eventData)
    {
        itemCanvasGroup.blocksRaycasts = false;
        DragPos(eventData);
    }
    public void OnEndDrag(PointerEventData eventData)
    {
        OnPointerEnter(eventData);
        itemCanvasGroup.blocksRaycasts = true;
        itemCanvasGroup.alpha = 1;
        isDragging = false;
    }
    public void OnPointerEnter(PointerEventData eventData)
    {
        if (eventData.pointerCurrentRaycast.depth == 0 && isDragging == true)
        {
            SetLastPos();
            return;
        }
        objectTag = eventData.pointerCurrentRaycast.gameObject.tag;
        if (objectTag != null && isDragging == true)
        {
            Debug.Log("放置位置：" + eventData.pointerCurrentRaycast.gameObject.name);
            MoveSiblingItem hitItem = eventData.pointerCurrentRaycast.gameObject.GetComponent<MoveSiblingItem>();
            if (hitItem != null)
            {
                if (itemlevel <= hitItem.itemlevel)
                {
                    Transform aimParent = eventData.pointerCurrentRaycast.gameObject.transform.parent;
                    while (true)
                    {
                        MoveSiblingItem aimParentSiblingItem = aimParent.GetComponent<MoveSiblingItem>();
                        if (aimParentSiblingItem == null)
                        {
                            break;
                        }
                        else
                        {

                            if (itemlevel > aimParentSiblingItem.itemlevel)
                            {
                                break;
                            }
                            else
                            {
                                hitItem = aimParentSiblingItem;
                                aimParent = aimParent.parent;
                            }
                        }
                    }
                    itemSelf.transform.SetParent(aimParent);
                    itemSelf.transform.SetSiblingIndex(hitItem.transform.GetSiblingIndex());
                }
                else
                {
                    itemSelf.transform.SetParent(eventData.pointerCurrentRaycast.gameObject.transform);
                }
                RefreshContentSizeFitter();
            }
            else
            {
                SetOriginalPos(itemSelf);
            }
        }
    }
    public void RefreshContentSizeFitter()
    {
        ContentSizeFitter[] csfs = itemRoot.GetComponentsInChildren<ContentSizeFitter>();
        foreach (var item in csfs)
        {
            LayoutRebuilder.ForceRebuildLayoutImmediate(item.GetComponent<RectTransform>());
        }
    }
    public void SetLastPos()
    {
        itemSelf.transform.SetParent(itemRoot.transform);
        RefreshContentSizeFitter();
    }
    public void SetOriginalPos(GameObject gameobject)
    {
        gameobject.transform.SetParent(originalSlot.transform);
        if (itemSelf.transform.GetSiblingIndex()== frontIndex)
        {
            itemSelf.transform.SetSiblingIndex(0);
            itemSelf.transform.SetSiblingIndex(frontIndex);
        }
        else
        {
            itemSelf.transform.SetSiblingIndex(frontIndex);
        }
        RefreshContentSizeFitter();
    }
    //获取鼠标当前位置，并赋给item
    private void DragPos(PointerEventData eventData)
    {
        RectTransform RectItem = itemSelf.GetComponent<RectTransform>();
        Vector3 globalMousePos;
        if (RectTransformUtility.ScreenPointToWorldPointInRectangle(itemSelf.transform as RectTransform, eventData.position, eventData.pressEventCamera, out globalMousePos))
        {
            RectItem.position = globalMousePos;
        }
    }
}

 

 这样就可以拖拽了！