I just ran into an issue with iOS that had me scratching my head. We have a Vimeo integration in an iframe that was playing on click on iOS safari (as evidenced by sound and network) but none of our JS handlers were being triggered.
The same site on Chrome and others would work fine and our JS handlers would be triggered, specifically an image on top of the iframe bound to click.
The problem turned out to be a Z-Index issue but somehow, the apparent/perceived/visible z-index was different from the interaction/touch/collision detection z-index. Increasing the Z-Index on the image gave it the priority it needed to be clickable.
Yuji Tomita 