Storing Config Settings in Xamarin Forms

Hi,
I'm just wondering has anyone any experience in having to store things like a URL to a REST API etc that your app is dependent on?
I've been investigating what is the best practice for this scenario and coming from a web background with web.config in mind I'm not seeing anything definite other than just in a class which seems a bit ad-hoc.
Would love to hear what ye're thoughts are on this as I'm just looking for the best practice.