Wrap-Up

As you can see, the WatchKit extension delegate performs many of the same tasks as an app delegate on iOS. The API is a bit pared down to coincide with the more streamlined feature set of watchOS, but through a few simple pieces of implementation, a well-designed extension delegate can make the difference between an average Apple Watch app and an exquisite one. You’ve seen how to take advantage of the extension’s lifecycle to ensure a seamless UI experience for your app, how to use Handoff to open your app right to the information a user was looking at in your Glance, and how to use notifications to allow users to perform actions at the raise of a wrist. Next, let’s look at how your code can reach outside the extension and communicate with other devices, using external networks to open a fountain of data possibilities.