It isn't. Simulators are still a thing, but they're not like Corellium. They may look like iOS but they can't run iOS apps or iOS binaries (apps have to be compiled specifically for the simulator). That's because the simulator is just an app that looks like iOS, but works completely differently on the inside.
thanks for the info! great to know!
...well thats lame...and dramatically nerfs my ability to effectively debug layout issues