App rejected for IPv6 network problem using Unity IAP service on Unity 5.4 iOS

I just had my app rejected from the App Store for the same reason. I am using the latest Unity x5.5.1. I doubt it has anything to do with IPv6 specifically since Apple told me they didn't even try to test it on IPv4. Rather I think it's just a glitch with Unity's Purchasing agent that can happen to anyone at any time.

If you borrowed the sample Purchaser script from the Unity tutorial like I did, you will notice that there is no provision for an initialization failure. If OnInitializedFailed() is called, all it does is print a Debug.Log statement. Then that's it. The store is dead if you try to access it.

Instead of inadvertently giving up like that, I had the OnInitializedFailed() method call InitializePurchasing() again a few more times. Specifically I setup a watchdog counter and incremented:

 public void OnInitializeFailed(InitializationFailureReason error)
     {
         // Purchasing set-up has not succeeded. Check error for reason. Consider sharing this reason with the user.
         if (initFailWatchdog++ < 100) InitializePurchasing();
         else Debug.Log("Tried 100 times to initialize IAP store without success.");
     }

I don't know if 100 is the right number, maybe 10 would work. Maybe you could try every second forever instead of a fixed amount of times.

There's more to be done to make this solution robust (for example: what happens if there's no network connection, or the user turns on his network after all those initialization attempts), but it got me past the App Store approval.

@Triggly_Glix,

This is also being discussed on this forum thread, which might be helpful: http://forum.unity3d.com/threads/ios-submission-failed-due-to-purchase-failed-on-ipv6-only-wifi.428044/#post-2767624