Login/authentication without user interaction

[Secorda]

We're developing a new iOS app for our customers. It will enable them to pick available slots (date and time) to make a reservation with our company.
These free slots are calculated based on the data of our company's google calendar account. It contains to calendars with our opening times and the occupied slots. Since our app only needs to access our own account (= our 2 google calendars) there's no need for user interaction (regarding the login to google services). Of course we don't want to show our login/password to the customers either.

There is no need to access any customers' accounts/data.

The xml-based gdata-objectivec-client used to support ClientLogin which was exactly what we needed. But it is deprecated now.

The new JSON-based google-api-objectivec-client only supports OAuth(1.0/2.0). As far as I understand, OAuth always requires some kind of user interaction. Is there any way to accomplish the same goal (login without user interaction) with the new api?

Any suggestion/solutions are highly appreciated!

Thank you.

[Greg Robbins]

You'll likely need a server-based app and a service account to talk to the Google Calendar API.

https://developers.google.com/accounts/docs/OAuth2ServiceAccount

I'm not certain about the current status of service account support for the Google Calendar API.

Otherwise, you'd need to hardcode or deliver a refresh token to the app.

Try asking in the Calendar API forum, https://groups.google.com/d/forum/google-calendar-api