With the update, outside developers can make apps specifically for the watch and interact directly with its sensors and controls. That will enable apps that analyze golf swings or record audio. Before, third-party apps have been limited to being extensions of apps that run on the iPhone.

The new software will be available as a free download starting next Wednesday.

At an event in San Francisco Wednesday, Apple said there are now 10,000 apps designed for the watch, including ones from Facebook and GoPro — the later using the watch's screen as a viewfinder for the video camera. Apple says the new capabilities will also allow additional health-related apps.