One of the new challenges of working with extensions such as WatchKit extensions is that since they run on a separate layer from your app you’ll need to add in a mechanism for data updates.

Here’s an open source library from Conrad Stoll of Mutual Mobile that allows you to easily create a bridge between an iOS extension and it’s application so you can easily pass data between the two locations called MMWormhole.

CFnotificationCenter is supported, and the end result is simple near instant updates on both sides when a message is sent using MMWormhole.

You can read more about MMWormhole on the Mutual Mobile blog.

You can find the repository on Github here.