Fixed positioning in Mobile Safari

This fixed position div can be achieved in just 2 lines of code which moves the div on scroll to the bottom of the page.

window.onscroll = function() {
  document.getElementById('fixedDiv').style.top =
     (window.pageYOffset + window.innerHeight - 25) + 'px';
};

iOS 5 has support for position:fixed.

See Google's solution to this problem. You basically have to scroll content yourself using JavaScript. Sencha Touch also provides a library for getting this behavior in a very performant manor.

it worked for me:

function changeFooterPosition() {   
  $('.footer-menu').css('top', window.innerHeight + window.scrollY - 44 + "px");
}

$(document).bind('scroll', function() {
  changeFooterPosition();
});

(44 is the height of my bar)

Although the bar only moves at the end of the scroll...

This may interest you. It's Apple Dev support page.
http://developer.apple.com/library/ios/#technotes/tn2010/tn2262/

Read the point "4. Modify code that relies on CSS fixed positioning" and you will find out that there is very good reason why Apple made the conscious decision to handle fixed position as static.