I've spent the last few weeks looking into workarounds regarding IOS, as my own content requires multiple nested IFrames in order to work.

IOS has huge problems regarding how it displays absolutely positioned content. This is caused by the way it treats the entire IFrame as a viewport (visible part of the page), where other browsers look at the visible part of the page.

There's an extension Called IOS fix that should help with that. alternatively, you can edit the JavaScript within the modules triggering the overlays to replace the overlays with alerts when on IOS.