This is for 3rd party apps -- despite the &quot;native&quot; 2.0 SDK, where all your code runs on the watch, it&#x27;s still split clumsily into app (which you can only control by providing interface templates) and extension, which is where your code runs. The extension can control the app only through a very limited SDK that has to do IPC to effect changes in the main app.<p>Apple&#x27;s own apps don&#x27;t have this restriction, and I can&#x27;t see a good one for 3rd party apps to have it, either -- hopefully they&#x27;ll open up a full API in the future.