Book Image

Mastering Xamarin.Forms - Second Edition

By : Ed Snider
Book Image

Mastering Xamarin.Forms - Second Edition

By: Ed Snider

Overview of this book

Discover how to extend and build upon the components of the Xamarin.Forms toolkit to develop 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 and geo-location, as well as how to loosely use these services in the app 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 logic through unit tests. Finally, we will setup Visual Studio App Center to automate building, testing, distributing and monitoring the app.
Table of Contents (11 chapters)

Creating and using platform-specific services

We have already created a service to handle navigation in the previous chapter. That custom navigation service specification was provided by the INavService interface and there is a property of that interface type in the BaseViewModel so that a concrete implementation of the service can be provided to the ViewModels as needed.

The benefit of using an interface to define platform-specific or third-party dependency services is that it can be used in an agnostic way in the ViewModels, and the concrete implementations can be provided via dependency injection. Those concrete implementations can be actual services, or even mocked services for unit testing the ViewModels, as we'll see in Chapter 8, Testing.

In addition to navigation, there are a couple of other platform-specific services our TripLog app could use to enrich its data and...