Book excerpt: Intended for readers with some existing experience of iOS development, watchOS 2 App Development Essentials has been fully updated for watchOS 2, Swift 2 and Xcode 7. Beginning with the basics, this book provides an introduction to WatchKit apps and the watchOS 2 app development architecture before covering topics such as tables, navigation, user input handling, maps, menus, working with images and videos and the recording and playback of audio. More advanced topics are also covered throughout the book, including communication and data sharing between a WatchKit app and the parent iOS app using the WatchConnectivity framework, working with custom fonts, user interface animation, clock face complications and the design and implementation of custom notifications. As with all the books in the "Development Essentials" series, watchOS 2 App Development Essentials takes a modular approach to the subject of app development for the Apple Watch, with each chapter covering a self-contained topic area consisting of detailed explanations, examples and step-by-step tutorials. This makes the book both an easy to follow learning aid and an excellent reference resource.