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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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Profile Icon Hernandez Profile Icon Ed Snider
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€13.98 €19.99
Full star icon Full star icon Full star icon Full star icon Half star icon 4.4 (15 Ratings)
eBook Mar 2018 192 pages 2nd Edition
eBook
€13.98 €19.99
Paperback
€24.99
Subscription
Free Trial
Renews at €18.99p/m
Arrow left icon
Profile Icon Hernandez Profile Icon Ed Snider
Arrow right icon
€13.98 €19.99
Full star icon Full star icon Full star icon Full star icon Half star icon 4.4 (15 Ratings)
eBook Mar 2018 192 pages 2nd Edition
eBook
€13.98 €19.99
Paperback
€24.99
Subscription
Free Trial
Renews at €18.99p/m
eBook
€13.98 €19.99
Paperback
€24.99
Subscription
Free Trial
Renews at €18.99p/m

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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

Product Details

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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 : 9781788297349
Vendor :
Microsoft
Category :
Languages :

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Product Details

Publication date : Mar 27, 2018
Length: 192 pages
Edition : 2nd
Language : English
ISBN-13 : 9781788297349
Vendor :
Microsoft
Category :
Languages :

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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
(15 Ratings)
5 star 66.7%
4 star 6.7%
3 star 26.7%
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Amz Buyer Oct 08, 2019
Full star icon Full star icon Full star icon Full star icon Full star icon 5
For beginners who are starting up with Xamarin, this is a good book. This helped me kick start.
Amazon Verified review Amazon
mdl Nov 13, 2018
Full star icon Full star icon Full star icon Empty star icon Empty star icon 3
Good introduction, but as an experienced Xamarin developer I was very underwelmed.
Amazon Verified review Amazon
J. Dansie Nov 12, 2018
Full star icon Full star icon Full star icon Empty star icon Empty star icon 3
The book starts out well enough with good information on Xamarin Forms. It was annoying trying to track down unexplained permission issues in the Xamarin Forms manifest to stop the Xamarin Forms Maps from crashing. The learning curve in Chapter 3 - Navigation goes about vertical for a novice. There is almost zero discussion about namespaces or included system libraries that are needed for the examples. There is LINQ code dependency put in without mention (LINQ is great, but, it's also a complicated rabbit-hole for a novice). The brief mention that the author decided to create a ViewModel centered navigation service to follow MVVM principles rather than a view centered navigation made me curious, so I did some digging into MVVM, MVC, MVPVM, and how it all applies to Xamarin Forms.There is an ideological architectural 'purity' debate raging in the various forums that Xamarin Forms users frequent about navigation in Xamarin Forms. Whether apps should tie 1:1 pages with ViewModels or whether it is better to center navigation on pages (views) and handle the details in the ViewModel. The author subscribes to the ViewModel centered navigation and goes through an ingenious, but, complicated setup of implementing a navigation service model starting from setting up an interface and then implementing a XamarinFormsNavService based on that interface. It is useful practice and information, but, there is little explanation and zero hand-holding. The reader must understand LINQ, reflection, threading tasks and dependency fairly well or they will be in for some serious roadblocks.For a seasoned c# or .Net developer this is a fine book. For a novice such as myself with just a few month in C#, I will probably look for another Xamarin Forms book after I run through the examples in the chapters as well as I can. I don't appreciate the reliance on 3rd party apps and Azure, but, it's all interesting stuff to learn I suppose.
Amazon Verified review Amazon
Amazon Customer Oct 14, 2018
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
I have been working with this book, page by page, and am surprised to find that already, at the time of this review (October, 2018) it's already been affected by changes. That being said, it's a great primer with a thorough step-by-step instruction on how to put an application together using MVVM and Xamarin forms (and providing some light on the elusive XAML). What's missing is the Whys. Why am I writing this line of code, how does it affect the underlying architecture of Xamarin.I will admit, trying to figure out Xamarin by looking at Youtube videos is a complete bust, and this book has become a blessing in as much as I can actually get something working. It is because of a thorough understanding of the .Net framework that I can comprehend what's being written. Not for the novice, and to the writer's credit, he does state that.Definitely worth the few bucks compared to some of the more books available out there.
Amazon Verified review Amazon
Kevin Gaynor Aug 13, 2018
Full star icon Full star icon Full star icon Empty star icon Empty star icon 3
I was enjoying following the book and the application that was being built but ran into several code issues as the content became more advanced meaning I frequently had to lean on my own expertise (it just didn't look right in the book) or in some cases, revert to the source code supplied. The application also goes through several re-writes; why not give us the best practice method first instead of going over the same classes re-writing them to make them better?
Amazon Verified review Amazon
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