Convert Mouse Input to Touch Input

Hello everyone, I am having a bit of trouble trying to transform my code to use touch inputs.
First of all, my game is working with mouse functions also on mobile, but I get some warnings when exporting the project, so I would like to get rid of them and make something "cleaner".
I have some objects and the goal is to swap 2 objects if one is dragged towards another one. My working code using mouse functions is this (it is attached to every object involved in the possible swap):

 void OnMouseOver(){ 
 
     if (Input.GetMouseButtonDown (0)) 
             pressed = true;            
 }
 
 void OnMouseExit() {                    
         if(pressed){
             pressed = false;                
             screenPoint = Camera.main.WorldToScreenPoint (gameObject.transform.position);            
             Vector3 currentScreenPoint = new Vector3 (screenPoint.x, Input.mousePosition.y, screenPoint.z);
 
             if (currentScreenPoint.y < screenPoint.y && num < 9) {
                 masterScript.SwapPlayerBlocks (num, num + 1);
             } 
             else if (currentScreenPoint.y > screenPoint.y && num > 0) {
                 masterScript.SwapPlayerBlocks (num, num - 1);
             }    
          }
 }

I tried to modify the code to make it work for touch and I came up with something like this:

 void Update(){
         foreach (Touch touch in Input.touches){    
             if (guiTexture.HitTest (touch.position))
                 pressed = true;
 
             else if (!guiTexture.HitTest (touch.position)){
                 if(pressed){
                     pressed = false;
                     screenPoint = Camera.main.WorldToScreenPoint (gameObject.transform.position);
 
                     if (touch.position.y < screenPoint.y && num < 9) { 
                         masterScript.SwapPlayerBlocks (num, num + 1);
                     } 
                     else if (touch.position.y > screenPoint.y && num > 0) { 
                         masterScript.SwapPlayerBlocks (num, num - 1);
                     }    
                 }
             }
         }
     }

But this doesn't seem to work... where could the problem be? Is it the good way to achieve what I need?