A look at think app blog about apple watch

this tutorial basically walk through the Apple’s Sample App for Apple Watch, Watchkit Catalog. 

Watch kit acts a a conduit that connects to the watch kit extension which resides in the iPhone app and orchastrates the watch app interface. 

When the user interacts with the watch interface, WatchKit signals to the paired iPhone and Watchkit extension then creates the objects at runtime needed to manage 

the appropriate screens the user interacts with. 

The watch kit architecture is like below 

If one need to add a watch kit app to a project, below step can be followed 

file -> New > Target -> and then select Apple Watch. 

On this screen we can select whether we need glance or Notification. 

Notification can be two, static and dynamic.

Once we create glance or notification, we can run that by selecting the executable accordingly by creating a new target. 

References:

http://thinkapps.com/blog/development/how-to-develop-apple-watch-apps/