Comment by 0x0

The scanner isn't foolproof. You could fool it if you obfuscate your calls to performSelector well enough, for example

if jsonResponseFromYourBackend contains:"runThis" then performSelector:json["runThis"]

and make sure you don't send a runThis param while the app is in review.

Unfortunately for Apple's app review process, Apple's own objective-C language and runtime has very strong dynamic reflection capabilities.