My last release of application which is 12.8 is rejected by apple saying that i have to add the IPv6 support to the app, I read and reviewed the recommended apple doc named Supporting IPv6 DNS64/NAT64 Networks https://developer.apple.com/library/content/documentation/NetworkingInternetWeb/Conceptual/NetworkingOverview/UnderstandingandPreparingfortheIPv6Transition/UnderstandingandPreparingfortheIPv6Transition.html#//apple_ref/doc/uid/TP40010220-CH213-SW1 thoroughly and came to know that already i am using the NSURLConnection class for network connectivity which is mentioned in the same doc, you can see the image from doc under section "Ensuring IPv6 DNS64/NAT64 Compatibility" mentioning the name of NSURLConnection class as a one of recommended class, below is that image
See the Recommended column in above image,