Improve the support of tactile device

-> The lazyload is not support by iOS device (see vvo#59)
-> Add a listener on the touchmove event that is fired before the scroll event.

lazyload.js

@@ -42,7 +42,8 @@ if (!window['lzld']) {
 
       // throttled functions, so that we do not call them too much
       saveViewportT = throttle(viewport, 20),
-      showImagesT = throttle(showImages, 20);
+      showImagesT = throttle(showImages, 20),
+      isiOSDevice = /(iPad|iPhone|iPod)/g.test( navigator.userAgent );
 
     // Override image element .getAttribute globally so that we give the real src
     // does not works for ie < 8: http://perfectionkills.com/whats-wrong-with-extending-the-dom/
@@ -175,11 +176,13 @@ if (!window['lzld']) {
     // img = dom element
     // index = imgs array index
     function showIfVisible(img, index) {
+      // Note that iOS devices freeze DOM manipulation during scroll, queuing them to apply when the scroll finishes.
+      // So it's better to disable the lazyloading on iOS device.
       // We have to check that the current node is in the DOM
       // It could be a detached() dom node
       // http://bugs.jquery.com/ticket/4996
-      if (contains(document.documentElement, img)
-        && img.getBoundingClientRect().top < winH + offset) {
+      if (isiOSDevice || (contains(document.documentElement, img)
+        && img.getBoundingClientRect().top < winH + offset)) {
         // To avoid onload loop calls
         // removeAttribute on IE is not enough to prevent the event to fire
         img.onload = null;
@@ -240,13 +243,15 @@ if (!window['lzld']) {
       unsubscribed = true;
       removeEvent(window, 'resize', saveViewportT);
       removeEvent(window, 'scroll', showImagesT);
+      removeEvent(window, 'touchmove', showImagesT);
       removeEvent(window, 'load', onLoad);
     }
 
     function subscribe() {
       unsubscribed = false;
       addEvent(window, 'resize', saveViewportT);
       addEvent(window, 'scroll', showImagesT);
+      addEvent(window, 'touchmove', showImagesT);
     }
 
     function overrideGetattribute() {