Beginning in June, developers with iOS apps will need to ensure they support the IPv6 networking protocol, as Apple will drop support for IPv4. Announced on the Apple Developers website, the message is clear: “Starting June 1, 2016 all apps submitted to the App Store must support IPv6-only networking.”
Apple states this shouldn’t mean major changes for developers, as IPv6 is already supported by NSURLSession and CENetwork APIs, but if hard-coded IP addresses that operate on IPv4-specific APIs are used, then it’ll be necessary to make some alterations. Apple provides some documentation on this here.
The IPv4 protocol is still used extensively, but IPv6 is being used more frequently by mobile networks around the world, and moving over to it now is becoming more important for those involved in the industry. Apple explains the importance of IPv6 here, and there’s a handy, online IPv6 readiness test here.