Handle Multitouch

if (Input.touchCount > 0)
{
    // Playing on an iOS device. Multi-touch.
    foreach (Touch touch in Input.touches)
    {
        if (touch.phase != TouchPhase.Ended && touch.phase != TouchPhase.Canceled)
        {
            MyProcessTouchHeldDownMethod(touch.position);
        }
    }
}
else if (Input.GetMouseButton(0) == true)
{
    // Playing in the Editor. Single-touch.
    MyProcessTouchHeldDownMethod(Input.mousePosition);
}