safari on iOS will revert to not allowing the camera and mic after it's already been "Allowed". For example, when switching from the back camera to the front.
Here is the source: https://github.com/doxyme/angular-tokbox/blob/master/opentok-angular.js
But our Safari demo and a sample (https://jsfiddle.net/xajprcyn/16/) created by me is working fine. It might be Angular specific or something else.