iOS应用因崩溃遭App Store拒审，本地及模拟器测试正常求排查

My iOS app was rejected from the App Store due to a crash during sign-in, but it runs fine on my local devices and simulators. Apple's rejection details are:

When we run your app on iPhone and iPad running iOS 11.3.1 connected to an IPv6 network, your app crashes after entering credentials and tapping the SIGN IN button.
We have attached detailed crash logs to assist with troubleshooting.

I don't have access to an IPv6 network environment—here's how to diagnose and fix the issue:

1. Analyze the Crash Log First #

Unzip the provided crash log and import it into Xcode via Window > Organizer > Crashes. Look closely at the call stack trace to identify the exact line or function where the crash occurs. Common culprits include:

• IPv4-specific network APIs (like gethostbyname()) that fail in IPv6-only environments
• Hardcoded IPv4 addresses that can't resolve in IPv6
• Low-level socket configurations that don't support IPv6

2. Simulate an IPv6 Network on Your Mac #

Apple provides a way to create an IPv6-only test network right from your Mac—no external IPv6 connection needed:

• Connect your Mac to a Wi-Fi network (this will be your internet source).
• Open System Preferences > Sharing.
• Select Internet Sharing, set "Share your connection from" to your Wi-Fi, and check the box for "To computers using" (choose "iPhone USB" if your device is plugged in, or "AirPort" for wireless testing).
• Click Options, then check "Create IPv6 local network" and save.
• Connect your iOS device to this shared network, and you can now reproduce the login crash exactly as Apple did.

3. Audit Your Network Code for IPv6 Compatibility #

Once you can reproduce the issue, fix these common compatibility gaps:

• Replace outdated APIs: Swap gethostbyname() with getaddrinfo() (supports both IPv4 and IPv6) for domain resolution.
• Avoid hardcoded IPs: Always use domain names instead of hardcoding IPv4 addresses—they won't resolve in an IPv6 network.
• Update socket setup: If using low-level sockets, use AF_INET6 instead of AF_INET to create IPv6-compatible sockets. Handle IPv4-mapped IPv6 addresses if your backend still uses IPv4.
• Check server support: Run nslookup -type=AAAA your-domain.com in Terminal to verify if your backend has an IPv6 address. If not, work with your server team to enable IPv6 support—Apple requires apps to function in IPv6-only networks.

4. Retest and Submit #

After fixing the issue, retest the login flow in your simulated IPv6 network to confirm the crash is gone. Then resubmit your app for review with a note explaining the fix you implemented for IPv6 compatibility.

内容的提问来源于stack exchange，提问作者Mohammad Ghanem