HealthKit is a new API provided by iOS 8. It enables apps to read the user's health information using the native Health app in their devices. You can consider that the Health app is a user interface for the HealthKit store. Other apps can write data in the Health app, such as workouts results, or statistics, so that the user can access them. This helps users to find all the information about their health in one location. The health information is stored in a secure location, and the user is responsible for deciding which data can be shared with apps. In the Health app, users can view, add, delete, and manage all their health data, and can also edit all the permissions to the third-party apps. HealthKit can also work with fitness or health devices, and it can save data from Bluetooth heart rate monitors. If your device has an M7 motion processor, HealthKit can import the step count data to it. So, all the developers who care about health and fitness apps will need to work...