Book Image

Mastering Xamarin.Forms - Second Edition

By : Hernandez, Ed Snider
Book Image

Mastering Xamarin.Forms - Second Edition

By: Hernandez, 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 a navigation service

In a typical multi-platform mobile app architecture, one would have to implement a platform-specific navigation service for each platform the app supports. In our case, Xamarin.Forms has already done this, so we will simply implement a single navigation service that extends the Xamarin.Forms navigation abstraction so that we can perform ViewModel-to-ViewModel navigation.

The first thing we will need to do is define an interface for our navigation service that will define its methods. We will start with an interface so that the service can be added to ViewModels via constructor injection, which we'll dive into in Chapter 4, Platform-Specific Services and Dependency Injection, and we can easily provide alternative implementations of the service without changing ViewModels that depend on it. A common scenario for this is creating a mock of the service...