I am going to publish an app on Apple Store then I came to know about IPV6 rejection issue. My app only support for IPV4 and on this link I found that app should support IPV6.
So my question is that, Is it compulsory that app must support for both IPV4 & IPV6?
Sorry if looks as a foolish question but I am looking for a Apple link & more detail before getting rejected from Apple.
You don't need to worry about IPv6 support, if you've not set hard-core IPv4 IP address in your web server/service url connection.
This Apple document will help you: Supporting IPv6-only Networks
All apps submitted to the App Store must support IPv6-only networking. A majority of apps will not require any changes as IPv6 is already supported by NSURLSession and CFNetwork APIs. However, if your app utilizes IPv4-specific APIs or hard-coded IP addresses, you will need to make changes. Be sure to test for IPv6 compatibility before submitting your app to the App Store for review.
However, Apple guides in Testing your app in an IPv6-only environment:
You should test your app on an IPv6-only network. If you don’t have one, you can set up a test network by following the instructions in Test for IPv6 DNS64/NAT64 Compatibility Regularly.
Following SO reference, faced similar problem, may guide you:
来源：https://stackoverflow.com/questions/48339092/apple-app-store-ipv6-requirement