I've installed Google Maps SDK for iOS thinking that I would get the directions between two places, like , the web API but following the tutorial what it seems is that it just opens the Google Maps app, which can also be done without the SDK. Am I understanding it wrong or the Google Maps SDK only offers open the app?
Thanks
Well, it depends exactly what you mean and want by "directions".
The Google Maps SDK for iOS does not itself do any sort of directions.
What you can do is use the Google Maps Directions web service to obtain information, then use that information to create a GMSPolyline which then can be rendered atop your in-app map. So basically it can show the line between point A and B, which is some level of directions, but may or may not be what you're wanting. Here's a YouTube video from Google that shows how to do this, and some sample code from Google's Mano Marks.
But if what you want are turn-by-turn directions, spoken directions, etc., no, the SDK cannot do that; you have to launch the external Google Maps app.