When attempting to log in to our Moodle site, which uses CAS authentication, via iOS v9.3.5, Moodle mobile gets all the way to where the user enters their CAS username and password, and then Safari returns an error message "Safari cannot open the page. The error was: 'The URL can't be shown'". The URL which Safari is trying to reach is: http://oursite.org/local/mobile/launch.php?service=local_mobile&passport=[passport number]&urlscheme=moodlemobile
I've even taken off the urlscheme to no avail. The URL comes back as an error in Chrome on iOS too, "This site can't be reached".
This works fine on Android.