Apple has notified developers that starting June 1, 2016, their apps will want to support IPv6-only networking. As that is already supported in Apple's frameworks, maximum apps would possibly not want to make a transformation.
At WWDC 2015 we introduced the transition to IPv6-only community products and services in iOS 9. Starting June 1, 2016 all apps submitted to the App Retailer will have to support IPv6-only networking. Maximum apps won't require any adjustments as a result of IPv6 is already supported by way of NSURLSession and CFNetwork APIs.
In case your app makes use of IPv4-specific APIs or hard-coded IP addresses, you are going to want to make some adjustments.