This generally shouldn’t be a problem for most iPhone and iPad MMO applications, although one Redditor noted that an older security key app for Star Wars: The Old Republic that might still be in circulation will be among those programs affected by the new operating system. There is a newer security key app out there, so if you use two-factor authentication for SWTOR, make sure you have the 2015 version of the app instead of the older launch edition.
Source: Reddit