App Rejected without IPV6

1. Open System preferences
2. Click sharing (To get NAT64Network Click Alt+Sharing)or(option+Sharing).

1) Make sure your Mac is connected to the Internet(with ethernet), but not through Wi-Fi.

2) Launch System Preferences from your Dock, LaunchPad, or the Apple menu.

3) Press the Option key and click Sharing. Don’t release the Option key yet. (don't forget to press option key)

4)Select Internet Sharing in the list of sharing services.

5)Release the Option key.

6)Select the Create NAT64 Network checkbox.

7)Choose the network interface that provides your Internet connection, such as Thunderbolt Ethernet or Only Ethernet.

8)Select the Wi-Fi checkbox.

9)Click Wi-Fi Options, and configure the network name and security options for your network.

10) Select the Internet Sharing checkbox to enable your local network.

11)When prompted to confirm you want to begin sharing, click Start

12) Now your mac mini is working as a hotspot and useing IPv6 NAT64 network

(looks like above image when hotspot created)

Now connect your iphone with your mac mini's hotspot. and Test your Application it's working properly or not.

I hope this answer is helpful you.

Edit :- Don't forget to add below frameworks.

1) WebKit

2) CFNetwork