Convert Raycast to 2D

I wrote this script from a tutorial, which helps with touch.Inputs. The problem is, the raycasts are 3d, but my game is 2D. I tried different ways to convert the raycasts in the script to 2d, but nothing have worked.
Can someone tell me how to need to be converted?

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class TouchInput : MonoBehaviour {

    public LayerMask touchInputMask;
    
    private List<GameObject> touchList = new List<GameObject>();
    private GameObject[] touchesOld;
    private RaycastHit hit;
	
	// Update is called once per frame
	void Update () {
        
        
#if UNITY_EDITOR
    
    if(Input.GetMouseButton(0) || Input.GetMouseButtonDown(0)  || Input.GetMouseButtonUp(0)) {
        
        touchesOld = new GameObject[touchList.Count];
            touchList.CopyTo(touchesOld);
            touchList.Clear();
 
        
        
                  Ray ray = GetComponent<Camera>().ScreenPointToRay(Input.mousePosition);
                
                  
                  if(Physics.Raycast(ray,out hit,touchInputMask)) {
                      
                      GameObject recipient = hit.transform.gameObject;
                      touchList.Add(recipient);
                      
                      if(Input.GetMouseButtonDown(0)) {
                          recipient.SendMessage("OnTouchDown", hit.point, SendMessageOptions.DontRequireReceiver);
                          
                      }  if(Input.GetMouseButtonDown(0)) {
                          recipient.SendMessage("OnTouchUp", hit.point, SendMessageOptions.DontRequireReceiver);
                          
                      }  if(Input.GetMouseButtonUp(0)) {
                          recipient.SendMessage("OnTouchStay", hit.point, SendMessageOptions.DontRequireReceiver);
                          
                      }  
                
	
                    }
                 
                 foreach (GameObject g in touchesOld) {
                     if(!touchList.Contains(g)) {
                         g.SendMessage("OnTouchExit", hit.point, SendMessageOptions.DontRequireReceiver);
                     }
                     
                 }
        
            }
    
#endif
        
        
        
        
        
    
        }
}

You have to use Physics2D.Raycast() instead of Physics.Raycast(). Just like this:

if(Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.mousePosition), Vector2.zero)
{
...
}

I haven’t tried it, so there might be some mistakes.