Smith William Smith 
Learning Xamarin Studio 

This book is intended for .NET developers with any level of experience and who are interested in building native applications without the hassle of becoming Objective-C or Java experts. Although it will be beneficial to have some development experience, particularly in .NET, Learning Xamarin help even a novice developer get past the headaches of setting up and customizing their new development environment so they can move on to producing high-quality native applications quickly.