After my conversation with the Apple rep where I discovered what the real cause of the rejection was, I replied to the review team on the review page giving a full explanation. Initially I got a pretty inane response thanking me for the information, and suggesting I fix the other issues identified by the review - there weren't any other issues! But after a few hours I started getting messages that the app was back in review, and then that it had been accepted. I have just released the app. I really feel that Apple need to improve their communication as to the real cause of rejection. I endured 3 weeks of utter discouragement and frustration, until the telephone conversation. Had they made it clear initially that the App had shown up as sharing a lot of common code with one other specific app, I would have have twigged much sooner. But the rejection message was ambiguous, and they failed to give clear answers to the questions I posted asking for more clarification, until the telephone conversation after my appeal had been rejected. Anyway I am much happier now. This does leave the original question open however. If different developers use a common, perhaps open source, engine to develop an app, are they going to run into trouble with the common engine code base being detected, and rejected as spam? And what can Apple do to avoid this situation? Or do they actually not want developers sharing a common engine for some reason?

If I type NSError I get no results found. If I type nserror (all lower case) I get the usual results and can go to the documentation for NSError. So it seems to be a case-sensitivity issue! This is in Google Chrome. On the same Windows 10 PC if I use Microsoft Edge, both NSError and nserror get the correct results. On my iMac Mini using Safari NSError gives no results, but nserror works.

Also broken in Safari on an iMac Mini