In addition to measuring temporary individual metrics, you can track complete workouts with HealthKit. Workouts can contain data like the number of calories burned during the workout, the workout duration, the number of strokes that were made during a swim, and more. The most convenient way to track workouts is by adding a watchOS version of your app that uses all of the sensors in the Apple Watch to track a workout. Since this book focuses on iOS development, you won't learn how to track workouts using an Apple Watch app. Instead, you will implement a workout app that only uses the iPhone to track a running workout.
In the code bundle for this chapter, you will find a project called Trekker. This app is a straightforward run-tracking app, where users can tap a button to start tracking a workout. Their GPS location is tracked, and then entered into HealthKit when the workout is complete. The user's route will also be stored in HealthKit by implementing the HKWorkoutRouteBuilder...