Android Drag Sprite代码Unity 5

using UnityEngine;

public class DragSprite : MonoBehaviour
{
    private bool isDragging = false;
    private Vector3 offset;

    void Update()
    {
        if (Input.touchCount > 0)
        {
            Touch touch = Input.GetTouch(0);

            if (touch.phase == TouchPhase.Began)
            {
                Vector3 touchPosition = Camera.main.ScreenToWorldPoint(touch.position);
                Collider2D collider = Physics2D.OverlapPoint(touchPosition);

                if (collider != null && collider.gameObject == gameObject)
                {
                    isDragging = true;
                    offset = transform.position - touchPosition;
                }
            }
            else if (touch.phase == TouchPhase.Moved && isDragging)
            {
                Vector3 touchPosition = Camera.main.ScreenToWorldPoint(touch.position);
                transform.position = touchPosition + offset;
            }
            else if (touch.phase == TouchPhase.Ended && isDragging)
            {
                isDragging = false;
            }
        }
    }
}