The app routing runs through React Native Router Flux. We've applied a middleware to Redux to track each screen view, and send the data to Google Analytics.
You could also extend the /src/lib/analytics.js middleware to include other tracking codes too. By default we've just included Google Analytics.
Setup your Google Analytics account and simply paste the tracking code to into the gaTrackingId variable in /src/constants/config.js
FYI you can have separate tracking codes for debug (to test tracking when your developing in debug mode) and production.
When setting up new scene to navigate to in /src/navigation/index.js, simply add the prop analyticsDesc to your scene. The value of this prop will be sent to Google Analytics, prefixed to the title prop (if that exists).
I usually like to send the {Component Name}: {Description of Screen} - {Navbar Title}. That way I can filter down to the data I need within Analytics.