Chapter 9
Creating Complications with ClockKit

You’ve learned a lot so far about making apps for the Apple Watch. These apps are great, but given that the Apple Watch is, well, a watch, aren’t there some watch-specific things we can do in our apps? The answer is an absolute yes. Many of the watch faces available on Apple Watch support complications, which are small pieces of data that appear on the watch face. The term complication is borrowed from the traditional watchmaking world. A diver’s watch, for instance, might feature a depth meter in addition to displaying the time. This depth meter is a complication. On Apple Watch, complications are extremely powerful, delivering bite-sized pieces of information to our users whenever they so much as check the time. In this chapter, you’ll learn about the ClockKit framework, which you can use to create complications for your own apps!

Apple Watch has a handful of built-in watch faces for users to choose from, and only some of those support third-party complications: Utility, Modular, Simple, Color, and Chronograph (shown in the figure). For those watch faces, the user can choose individual complications to use at various positions, and that’s where you come in. By providing your own complication using ClockKit, your app will appear in the list of complications, allowing users to install your app right on their watch face. This is prime real estate for any app, since these complications appear every time users raise their wrist to look at the watch.

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Figure 3. The Apple Watch faces that support third-party complications, from left to right: Utility, Modular, Simple, Color, and Chronograph

In this chapter, we’ll cover creating complications, providing data to them, and providing different complications for different watch faces.