Book Image

Mastering Xamarin.Forms

By : Ed Snider
Book Image

Mastering Xamarin.Forms

By: Ed Snider

Overview of this book

Discover how to extend and build upon the components of the Xamarin.Forms toolkit to develop an effective, robust mobile app architecture. Starting with an app built with the basics of the Xamarin.Forms toolkit, we’ll go step by step through several advanced topics to create a solution architecture rich with the benefits of good design patterns and best practices. We’ll start by introducing a core separation between the app’s user interface and the app’s business logic by applying the MVVM pattern and data binding. Discover how to extend and build upon the components of the Xamarin.Forms toolkit to develop an effective, robust mobile app architecture. Starting with an app built with the basics of the Xamarin.Forms toolkit, we’ll go step by step through several advanced topics to create a solution architecture rich with the benefits of good design patterns and best practices. We’ll start by introducing a core separation between the app’s user interface and the app’s business logic by applying the MVVM pattern and data binding. Then we will focus on building out a layer of plugin-like services that handle platform-specific utilities such as navigation, geo-location, and the camera, as well as how to use these services with inversion of control and dependency injection. Next we’ll connect the app to a live web-based API and set up offline synchronization. Then, we’ll dive into testing the app—both the app logic through unit tests and the user interface using Xamarin’s UITest framework. Finally, we’ll integrate Xamarin Insights for monitoring usage and bugs to gain a proactive edge on app quality.
Table of Contents (17 chapters)

Understanding the MVVM pattern


At its core, MVVM is a presentation pattern designed to control the separation between user interfaces and the rest of the application. The key elements of the MVVM pattern are as follows:

  • Models: Models represent the business entities of an application. When responses come back from an API, they are typically deserialized to models.

  • Views: Views represent the actual pages or screens of an application, along with all of the elements that make them up, including custom controls. Views are very platform-specific and depend heavily on platform APIs to render the application's user interface (UI).

  • ViewModels: ViewModels control and manipulate the Views by serving as their data context. ViewModels are made up of a series of properties represented by models. These properties are part of what is bound to the Views to provide the data that is displayed to users, or to collect the data that is entered or selected by users. In addition to model-backed properties, ViewModels...