Google has offered the Cast SDK to developers in some capacity for three years, but there have long been some annoyances that made it difficult to implement and maintain in certain apps. Cast SDK v3.0 was announced at I/O 2016 last month, and now it's available to developers. This version of the SDK seeks to simplify several elements of the old one to make developers' lives a little easier.
All of the documentation is live on the Google developer site with samples apps, tutorials, and more. The SDK includes a completely new version of the Cast framework that requires less code to integrate, and it's consistent across Android, iOS, and Chrome. Google is trying to take over more of the details of Cast in the SDK so developers don't need to manage as much in their own code. For example, the cast button, introductory overlay, device discovery, and playback controls are handled by the SDK now.
The documentation released today is just for the sender SDK (for your devices that send media). A new receiver SDK will be available soon with similarly streamlined features.
- Google Developers