Mastering Xamarin.Forms the Third Edition is a great book for both seasoned Xamarin developers and beginners just starting a Xamarin.Forms project. It is a great resource for many techniques needed to solve the complex problems of Xamarin.Forms application development.
Book Review: Mastering Xamarin.Forms Third Edition by Andrew Hoefling
Material Design is a Design concept from Google that determines the size, color, distance and layout of different controls. Google has designed both the design for Android and iOS. With Xamarin.Forms Material Visual, there is now an easy option to adapt this design concept for its own Xamarin.Forms apps. With just three simple steps, you can present your Android and iOS app in the material design look.
Note: Page is in German
Demo: Xamarin.Forms Material Visual by Sebastian Jensen
The latest and greatest Xamarin.Forms has a whole bunch of new triggers. These look like they will save you lots of code and help keep UI related tasks in your XAML.
Note: Page is in Spanish
[Xamarin.Forms] StateTriggers by Javier Suárez Ruiz