Strategy for selectively enabling features in a mobile application

Assuming an application that has no login, how can one go about allowing some of its user access to activate 'hidden' features.

An example I recently came across is the need for some users to see a different version of the data feed the app is using (official feed vs editor feed which is being modified/approved)

In android, I assume that we could just point those user to downloading a specific file and test for that file presence in the app but I dont believe this approach can be used on iOS (sandbox).

The approaches I came up with:

• Hide an activator in the UI: specific touches/gestures, invisible button and the like
• Make the user visit a site which sets a cookie when on a specific page and test for that cookie's value in the app to enable features.

Did someone came up with a more elegant solution?