I am also experiencing this issue and have isolated the issue to the label halos on my address point feature class. I'm not sure if 1 or 500 halos are causing the crash, but when I turn them off everything works fine. Funny thing is, everything was fine until it wasn't. I think an update of either iOS or Safari caused the halos to crash the browser. I also tried it in Chrome on an Ipad so that leads me to believe it is an iOS update issue.