思路：

1、生成一个点击特效实例，每点击屏幕，就调整特效实例的位置并控制特效的显隐状态即可。

2、需要注意要保证在编辑器开发时或手机上运行时都要显示点击效果。

方案一 （推荐）

using UnityEngine;
using UnityEngine.EventSystems;public class ScreenClick : MonoBehaviour,IPointerDownHandler
{public GameObject effectPrefab;//特效预制体private GameObject clickEffectInstance;private RectTransform _Rect;void Start(){_Rect = GetComponent<RectTransform>();clickEffectInstance = Instantiate(effectPrefab, transform);clickEffectInstance.SetActive(false);}public void OnPointerDown(PointerEventData eventData){clickEffectInstance.SetActive(false);RectTransformUtility.ScreenPointToWorldPointInRectangle(_Rect,eventData.position,eventData.enterEventCamera,out Vector3 pos);clickEffectInstance.transform.position = pos;clickEffectInstance.SetActive(true);}
}

方案二

using UnityEngine;public class ScreenClick : MonoBehaviour
{public GameObject effectPrefab;//特效预制体public Camera _Camera;private GameObject clickEffectInstance;private RectTransform _Rect;void Start(){_Rect = GetComponent<RectTransform>();clickEffectInstance = Instantiate(effectPrefab, transform);clickEffectInstance.SetActive(false);}void Update(){
#if UNITY_EDITORif (Input.GetKeyDown(KeyCode.Mouse0)){clickEffectInstance.SetActive(false);var screenPos = Input.mousePosition;ShowClickEffect(screenPos);Debug.Log("222");}
#elif UNITY_ANDROID||UNITY_IOSif (Input.touchCount > 0){var touch = Input.GetTouch(0);if (touch.phase == TouchPhase.Began){clickEffectInstance.SetActive(false);var screenPos = Input.GetTouch(0).position;ShowClickEffect(screenPos);Debug.Log("333");}}
#endif}/// <summary>/// 显示点击特效/// </summary>/// <param name="screenPos">点击的屏幕位置</param>private void ShowClickEffect(Vector2 screenPos){RectTransformUtility.ScreenPointToWorldPointInRectangle(_Rect, screenPos, _Camera, out Vector3 pos);clickEffectInstance.transform.position = pos;clickEffectInstance.SetActive(true);}
}