Apple says that developers need to be submitting their new apps that have been tested and the latest versions for WatchOS and iOS now. The company has set a deadline after which all apps need to be built with the newest SDK releases.
The company released the final versions of WatchOS 5 and iOS 12 in September and required that developers creating apps have features particular to those versions before submitting them for approval.
Furthermore, the developers need to know that from March 2019, all the apps they submit will need to be built with iOS 12 SDK. They will also need to support Xs Max – the newest version of the 6.5-inch screen iPhone.
The Watch Series 4 will utilize WatchOS 5 differently.
The situation is the same for WatchOS. During the same period, Apple will require apps to be built on WatchOS5 SDK and to work on Apple Watch Series 4.