iOS 5 fixed positioning and virtual keyboard

Question

I had this problem in my application. Here's how I'm working around it:

input.on('focus', function(){
    header.css({position:'absolute'});
});
input.on('blur', function(){
    header.css({position:'fixed'});
});

I'm just scrolling to the top and positioning it there, so the iOS user doesn't notice anything odd going on. Wrap this in some user agent detection so other users don't get this behavior.

I had a slightly different ipad issue where the virtual keyboard pushed my viewport up offscreen. Then after the user closed the virtual keyboard my viewport was still offscreen. In my case I did something like the following:

var el = document.getElementById('someInputElement');
function blurInput() {
    window.scrollTo(0, 0);
}
el.addEventListener('blur', blurInput, false);

This is the code we use to fix problem with ipad. It basically detect discrepancies between offset and scroll position - which means 'fixed' isn't working correctly.

$(window).bind('scroll', function () {
    var $nav = $(".navbar")
    var scrollTop = $(window).scrollTop();
    var offsetTop = $nav.offset().top;

    if (Math.abs(scrollTop - offsetTop) > 1) {
        $nav.css('position', 'absolute');
        setTimeout(function(){
            $nav.css('position', 'fixed');
        }, 1);
    }
});

The position fixed elements simply don't update their position when the keyboard is up. I found that by tricking Safari into thinking that the page has resized, though, the elements will re-position themselves. It's not perfect, but at least you don't have to worry about switching to 'position: absolute' and tracking changes yourself.

The following code just listens for when the user is likely to be using the keyboard (due to an input being focused), and until it hears a blur it just listens for any scroll events and then does the resize trick. Seems to be working pretty well for me thus far.

    var needsScrollUpdate = false;
    $(document).scroll(function(){
        if(needsScrollUpdate) {
            setTimeout(function() {
                $("body").css("height", "+=1").css("height", "-=1");
            }, 0);
        }
    });
    $("input, textarea").live("focus", function(e) {
        needsScrollUpdate = true;
    });

    $("input, textarea").live("blur", function(e) {
        needsScrollUpdate = false;
    });

Just in case somebody happens upon this thread as I did while researching this issue. I found this thread helpful in stimulating my thinking on this issue.

This was my solution for this on a recent project. You just need to change the value of "targetElem" to a jQuery selector that represents your header.

if(navigator.userAgent.match(/iPad/i) != null){

var iOSKeyboardFix = {
      targetElem: $('#fooSelector'),
      init: (function(){
        $("input, textarea").on("focus", function() {
          iOSKeyboardFix.bind();
        });
      })(),

      bind: function(){
            $(document).on('scroll', iOSKeyboardFix.react);  
                 iOSKeyboardFix.react();      
      },

      react: function(){

              var offsetX  = iOSKeyboardFix.targetElem.offset().top;
              var scrollX = $(window).scrollTop();
              var changeX = offsetX - scrollX; 

              iOSKeyboardFix.targetElem.css({'position': 'fixed', 'top' : '-'+changeX+'px'});

              $('input, textarea').on('blur', iOSKeyboardFix.undo);

              $(document).on('touchstart', iOSKeyboardFix.undo);
      },

      undo: function(){

          iOSKeyboardFix.targetElem.removeAttr('style');
          document.activeElement.blur();
          $(document).off('scroll',iOSKeyboardFix.react);
          $(document).off('touchstart', iOSKeyboardFix.undo);
          $('input, textarea').off('blur', iOSKeyboardFix.undo);
      }
};

};

There is a little bit of a delay in the fix taking hold because iOS stops DOM manipulation while it is scrolling, but it does the trick...