The OneSignal Android SDK by OneSignal is for using the OneSignal API with Android applications in Java. The OneSignal REST API allows developers to access the functionality of OneSignal for integration with other websites and applications. OneSignal is a push notification service for mobile and web applications and websites.
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.