From the ruling[0]:
> As to count one, we agree that Corellium is shielded by the fair use doctrine. First, Corellium’s virtualization software is transformative—it furthers scientific progress by allowing security research into important operating systems. Second, iOS is functional operating software that falls outside copyright’s core. Third, Corellium didn’t overhelp itself to Apple’s software. And fourth, Corellium’s product does not substantially harm the market for iOS or iOS derivatives—so Apple’s own incentive to innovate remains strong.
The important part here is that it proves Apple does not have the defacto right to claim infringement on iOS. If your emulator is transformative, offers functionality beyond default iOS, doesn't abuse their services and doesn't threaten the iOS market (eg. iPhones) it should be considered lawful. The interpretation is still open on the infringement of their wallpapers, icon and "contributory infringement", but this spells in pretty plain text that emulating iOS is fair game. Put another way, even a company that sells iOS emulators to hackers was found to not be in direct violation of Apple's iOS copyright.
[0] https://aboutblaw.com/7PK