WeatherApp is an example that accompanies Learn app-building basics with Xamarin.Forms in Visual Studio (MSDN Library).
It consists of a PCL that contains all the UI and business logic. The platform-specific projects for Android, iOS, and Windows are the minimal app stubs.
To use this sample, you must first sign up for a free API key at http://openweathermap.org/appid. Paste that key in place of YOUR API KEY HERE in the following line of WeatherApp/Core.cs:
string key = "YOUR API KEY HERE";
The equivalent app written with native UI layers, is WeatherApp (Native).
Kraig Brockschmidt, Nicole Haugen