Apple Encourages Developers to Update to watchOS 4

In a short note to developers on its Developer News and Updates site, Apple is encouraging developers to:

Take advantage of increased performance, new background modes for navigation and audio recording, built-in altimeter capabilities, direct connections to accessories with Core Bluetooth, and more. In addition, the size limit of a watchOS app bundle has increased from 50 MB to 75 MB.

The carrot of new functionality comes with something of a stick as well. After April 1, 2018, watchOS 1 app updates will no longer be accepted and all updates must be native apps built with the watchOS 2 SDK or later. New app submissions must be built with the watchOS 4 SDK.