Thanks for the quick reply.
'system' is deprecated: first deprecated in iOS 8.0 - Use posix_spawn APIs instead.
But posix_spawn isn't exactly like system(). They are quite different.
At the same time posix_spawn isn't available on tvOS and watchOS and it wouldn't be a surprise that calling it in an iOS application would either silently fail or flag your app as using APIs that shouldn't be used. Or even worse it might be removed in the next iteration of iOS.
It would probably help to speak with someone at Apple to understand the extent of the decision of removing system() entirely.
Cheers.