Trying to get fixed background image - iOS

[MikeJones89]

I'm trying to get a fixed background image, and only get the content to scroll (not the bg image). 

This is the style I am using:

   

.ui-body-a, .ui-overlay-a {
 background: #ffffff;
 background: url('images/mapc.jpg') no-repeat fixed;
    }

This works great on Desktop browsers (chrome etc...),  but on iOS the background image scrolls along with the content when scrolling.   I have tried various other ways by following what some people have answered on stackOverflow to no avail.  

Any help would be great