If you are registered as an Apple Developer, by now you should have received an email from Apple announcing release of WatchKit. WatchKit is the toolbox required to develop apps for the next-generation wrist-wear. Even though you won’t be able to publish your apps until next year since the Apple Watch hasn’t been launched yet, but you can start experimenting today.
WatchKit provides three opportunities to extend your iPhone app to Apple Watch: WatchKit apps, Glances, and actionable notifications.
Following is a getting started video posted by Apple Developer.
Source: Apple Developer