This section provides you with an overview of the WatchKit platform, which is a fundamental part of Apple Watch. When developing apps for Apple Watch, it takes advantage of the WatchKit framework that happens to be included as part of the iOS SDK, and both are embedded into the watchOS and iOS operating systems.
The WatchKit framework contains the necessary classes that provide the underlying functionality for both the WatchKit extension and the WatchKit application and is responsible for handling all of the communication between the WatchKit extension that runs on the iPhone device and its corresponding WatchKit application that is installed on Apple Watch.
Whenever you begin developing Apple Watch apps, you will notice that your project contains a number of different targets that make use of the WatchKit platform.
