I have a similar question as asked previously in the forum here. I have implemented the context menu in an app and it works with long press on android, but not on ios. I tried the esri context menu sample and it too fails on ios. I know that ios handles mouse events natively, and they don't bubble by default, but I have followed all the published advice, including adding 'pointer: cursor; to all nodes in the DOM, and created empty mouse events (click handlers) in the code, but I can only get alerts to work when inserted into the click handlers that I create, using touchstart or mousedown as the event, and even tried to use 'contextmenu' event, but that doesn't work on ios either. I can't tell how far the long press gets: It seems to be a problem with dojo menu.js, but I have not had the opportunity yet to debug an ipad on a mac (I use Windows at work, and the Chrome simulator cannot simulate native ios mouse events: the context menu works fine in the Chrome simulator).
I hope there is a work-around. I am using the bower build, so I do have access to the menu.js, if it is necessary to adjust anything there. Any help would be greatly appreciated.