Usually, Apple keeps its smartphone operating system iOS and computer operating system macOS separate from each other. However, there have been some instances when the Cupertino-based tech giant has allowed the users to sync some features across iOS and macOS; for example, Notes, Messages, Calendars, etc.
Previously there had been rumors about Apple planning to merge both these operating system platforms, however; Apple has always denied them. Now, it appears that instead of merging the two operating systems, Apple could be planning to borrow an idea from search giant Google book and develop a feature, which would let the users run different applications on both the platforms.
According to Daring Fireball’s John Gruber, he has received this piece of information from some second-hand sources. However, it is not clear as to what exactly this feature would do, but it sounds like the developers would be able to create only one version of an app that would run both on iOS and macOS following the launch of this cross-platform feature.
You should note that this is not the first time when we are hearing this kind of universal apps in the ecosystem of Apple. Back in 2017, Mark Gurman from Bloomberg had published a similar report; only Gurman had suggested that the tech giant would launch the feature in 2018 along with iOS 12 and macOS 10.14. Here, Gruber is claiming that the feature will not make it to the market until at least 2019.
Anyway, you should always take these kinds of rumors with a pinch of salt, as it has not been confirmed officially. So, we will only know more about it in the future.