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Mastering Xamarin.Forms
Mastering Xamarin.Forms

Mastering Xamarin.Forms: Build rich, maintainable, multi-platform, native mobile apps with Xamarin.Forms , Second Edition

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Mastering Xamarin.Forms

MVVM and Data Binding

In this chapter, we will take a look at the Model-View-ViewModel (MVVM) pattern, the MVVM elements that are offered with the Xamarin.Forms toolkit, and how we can expand on them to truly take advantage of the power of the pattern. As we dig into these topics, we will apply what we have learned to the TripLog app that we started building in Chapter 1, Getting Started.

In this chapter, we will cover the following topics:

  • Understanding the MVVM pattern and data binding
  • MVVM in the Xamarin.Forms toolkit
  • Adding the MVVM pattern and data binding to the Xamarin.Forms mobile app created in Chapter 1, Getting Started

Understanding the MVVM pattern

At its core, MVVM is a presentation pattern designed to control the separation between user interfaces and the rest of an 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...

Adding MVVM to the app

The first step of introducing MVVM into an app is to set up the structure by adding folders that will represent the core tenants of the pattern, such as Models, ViewModels, and Views. Traditionally, the Models and ViewModels live in a core library (usually, a portable class library or .NET standard library), whereas the Views live in a platform-specific library. Thanks to the power of the Xamarin.Forms toolkit and its abstraction of platform-specific UI APIs, the Views in a Xamarin.Forms app can also live in the core library.

Just because the Views can live in the core library with the ViewModels and Models, this doesn't mean that separation between the user interface and the app logic isn't important.

When implementing a specific structure to support a design pattern, it is helpful to have your application namespaces organized in a similar structure...

Summary

In this chapter, we updated the app that we started creating in Chapter 1, Getting Started, by removing data and data-related logic from the Pages, offloading it to a series of ViewModels, and then binding the Pages to those ViewModels. In the next chapter, we will expand on the Xamarin.Forms navigation service so that we can also move navigation code from the Pages to the ViewModels.

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Key benefits

  • Packed with real-world scenarios and solutions to help you build professional grade mobile apps with Xamarin.Forms
  • Build an effective mobile app architecture with the Xamarin.Forms toolkit
  • Maximize the overall quality of your Xamarin.Forms apps

Description

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.

Who is this book for?

This book is intended for C# developers who are familiar with the Xamarin platform and the Xamarin.Forms toolkit. If you have already started working with Xamarin.Forms and want to take your app to the next level with higher quality, maintainability, testability, and flexibility, then this book is for you.

What you will learn

  • Find out how, when, and why you should use architecture patterns and get best practices with Xamarin.Forms
  • Implement the Model-View-ViewModel (MVVM) pattern and data-binding in Xamarin.Forms mobile apps
  • Extend the Xamarin.Forms navigation API with a custom ViewModel-centric navigation service
  • Leverage the inversion of control and dependency injection patterns in Xamarin.Forms mobile apps
  • Work with online and offline data in Xamarin.Forms mobile apps
  • Test business logic in Xamarin.Forms mobile apps
  • Use platform-specific APIs to build rich custom user interfaces in Xamarin.Forms mobile apps
  • Explore how to improve mobile app quality using Visual Studio App Center
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Publication date, Length, Edition, Language, ISBN-13
Publication date : Mar 27, 2018
Length: 192 pages
Edition : 2nd
Language : English
ISBN-13 : 9781788290265
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Microsoft
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Product Details

Publication date : Mar 27, 2018
Length: 192 pages
Edition : 2nd
Language : English
ISBN-13 : 9781788290265
Vendor :
Microsoft
Category :
Languages :
Tools :

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Table of Contents

10 Chapters
Getting Started Chevron down icon Chevron up icon
MVVM and Data Binding Chevron down icon Chevron up icon
Navigation Chevron down icon Chevron up icon
Platform Specific Services and Dependency Injection Chevron down icon Chevron up icon
User Interface Chevron down icon Chevron up icon
API Data Access Chevron down icon Chevron up icon
Authentication Chevron down icon Chevron up icon
Testing Chevron down icon Chevron up icon
App Monitoring Chevron down icon Chevron up icon
Other Books You May Enjoy Chevron down icon Chevron up icon

Customer reviews

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Full star icon Full star icon Full star icon Full star icon Half star icon 4.4
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5 star 66.7%
4 star 6.7%
3 star 26.7%
2 star 0%
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Amazon Customer Apr 11, 2018
Full star icon Full star icon Full star icon Full star icon Full star icon 5
This book is an essential resource for anyone building cross platform apps with Xamarin.Forms. It is practical, straightfoward and well written and replete with good examples.
Amazon Verified review Amazon
Richard Taylor Jun 19, 2018
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Great information and read on Xamarin.Forms!
Amazon Verified review Amazon
Amazon Customer Apr 18, 2018
Full star icon Full star icon Full star icon Full star icon Full star icon 5
This is an excellent book. The author presents the information in a clear and concise manner. As a novice in Xamarin I was able to gain a great deal of understanding of Xamarin Forms.
Amazon Verified review Amazon
Amazon-klant May 23, 2018
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Good, succinct and quite to the point, clearly written and well explained code samples complete the explanations. A good introduction
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Amz Buyer Oct 08, 2019
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For beginners who are starting up with Xamarin, this is a good book. This helped me kick start.
Amazon Verified review Amazon
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