Sync public data, best practises

My app has some data that is common and not connected to a specific user.
I want to sync that data when the app starts and before anyone has logged in.
What is the best way to handle this?

-Make a specific hard coded user that has username and password in the source code and then sync? Update that user means new app version.
-Make a API user that has the API key in the source code and then sync? New API key means new app version.
-Create a separate distribution of the username/password that can be called by the app to sync public data?
-Or some other solution?

Thanks