Windows Phone 8 SDK comes with comprehensive API documentation and developer guides. You could also compliment the offering with Nokia Lumia Developer's Library which adds information on the application areas that offer especially interesting possibilities for developers on Nokia Lumia devices. The library provides detailed guides on the use of Map, Camera, NFC, and Nokia Music APIs with code snippets and references to the complete example applications. It also explains how to co-develop for Windows Phone 7 and 8 and how to port your existing Windows Phone 7 applications to Windows Phone 8.
Guide to the Maps: This guide describes how to use the new Windows Phone 8 Maps APIs. A simple browser application featuring maps – Map Explorer – is used as an example. Whether you are upgrading an application that uses Bing Maps, enhancing your already existing application by introducing a Map control, or starting to develop a whole new maps-based application with such features as keyword search, route directions and locationing, this guide will help you to accomplish your task. Read more..