Apple's HealthKit API enables health and fitness apps to share their data, both with the new iOS 8 Health application and with each other. HealthKit can serve as a hub for all the health and fitness apps on an iOS device. This allows consumers to have more oversight of their health and fitness.
Using the open source CareKit framework, developers can create apps that help users monitor and manage medical conditions and their overall health, and then share that data with healthcare pros. Here we run through the CareKit modules and how the pieces fit together, using sample Swift code.