Drag and DoubleTap from mouse to touch???

Greetings,

I've been bashing my head over this one for the past two days, and I just can't get it to work... I've been using the mouse controls for single touch controls on mobile devices. However I've noticed some hiccups here and there and would rather use the touch controls. I've checked the entire web for a solution but none worked for me for some reason... I've pasted the code I have atm for mouse, I need help converting that for touch controls.

THANK YOU in advance!

     void OnMouseDown()
         {
         distance = Vector3.Distance (transform.position,  Camera.main.transform.position);
    dragging = true;
             }
 void OnMouseUp()
     {
         dragging = false;
         if ((Time.time - doubleClickStart) < 0.3f)
         {
             this.OnDoubleClick();
             doubleClickStart = -1;
         }
         else
         {
             doubleClickStart = Time.time;
         }
 
 void Update()
     {    if (dragging) 
             {
                 Ray ray = Camera.main.ScreenPointToRay (Input.mousePosition);
                 Vector3 rayPoint = ray.GetPoint (distance);
                 transform.position = rayPoint;
             }
         }
     }