We have some tooltips running at my work that are used to render sharing buttons when a user clicks or taps on them. When the recent upgrade to iOS came around, the tooltips stopped being rendered properly in iOS 5.
After running into a few problems with jQuery Tools and the iPad, I came up with a solution for getting the tooltips to appear next to the anchor element like they were supposed to. By using the event.clientY value from the touch event, I was able to detect where in the DOM the touch had happened, and simply position the tooltip right next to it, with something like this:
$('#tooltip').css('position', 'absolute !important').css('top', event.clientY);
In iOS 4.3, event.clientY was reporting the absolute position of the touch event relative to the entire document. In iOS 5, I discovered that it was reporting the position of the touch event relative to the window. So, if you tapped a tooltip way down on the page, but near the top of the current viewport window, the tooltip would appear right near the top of the document, completely off screen.
A little digging on Google yielded this page on the Apple site. The reference to an event.pageY property made me think that maybe that would do the trick, and it seems to work.
$('#tooltip').css('position', 'absolute !important').css('top', event.pageY);
Now, with iOS 5, the touch event was properly setting the tooltip’s top value to the position of the touch event within the entire DOM, not just the viewport. I’m not exactly sure what’s changed between iOS 4.3 and 5, but at least now I have something that works for both.