<li>
 <div class="pic">
   <div class="overlay  touch">
     <div class="content">extra content here</div>
   </div>
  <img src="image.jpg" alt="" >
 </div>
</li>

$(".touch").on("mouseenter mouseleave touchstart", function(e){
   if(e.type == 'touchstart') {
     $(this).off('mouseenter mouseleave');
   }
  $(this).toggleClass("hover");
});