Preface

Xamarin.Forms Projectsis a hands-on book in which you get to create nine applications from the ground up. You will gain the fundamental skills you need in order to set up your environment, and we will explain what Xamarin is before we transition into Xamarin.Forms to really take advantage of truly native cross-platform code.

After reading this book, you will have a real-life understanding of what it takes to create an app that you can build on and that stands the test of time.

We will cover, among other things, animations, augmented reality, consuming REST interfaces, real-time chat using SignalR, and location tracking using a device's GPS. There is also room for machine learning and the must-have to-do list.

Happy coding!

Who this book is for

This book is for developers who know their way around C# and Visual Studio. You don't have to be a professional programmer, but you should have basic knowledge of object-oriented programming using .NET and C#. The typical reader would be someone who wants to explore how you can use Xamarin, and specifically Xamarin.Forms, to create applications using .NET and C#.

No knowledge of Xamarin is required in advance, but it would be a great help if you've worked in traditional Xamarin and want to take the step toward Xamarin.Forms.

What this book covers

Chapter 1,Introduction to Xamarin, explains the basic concepts of Xamarin and Xamarin.Forms. It helps you understand the building blocks of how to create a true cross-platform app. It's the only theoretical chapter of the book and will help you get started and set up your development environment.

Chapter 2,Building Our First Xamarin.Forms App, guides you through the concepts of Model-View-ViewModel and explains how to use the Inversion of Control pattern to simplify the creation of Views and ViewModels. We will create a to-do app that supports navigation, filtering, and the adding of to-do items to a list, and will also render a user interface that takes advantage of the powerful data-binding mechanisms in Xamarin.Forms.

Chapter 3, Building a News App Using Xamarin.Forms Shell, explores one of the biggest pieces of news in Xamarin.Forms 4 –Shell, a new way to define the structure of Xamarin.Forms apps. There is also a new navigation system. In this chapter, you will learn all you have to know to use Shell in a Xamarin.Forms app.

Chapter 4,A Matchmaking App with a Rich UX Using Animations, lets you dive deeper into how to define a richer user interface with animations and content placement. It also covers the concept of custom controls to encapsulate the user interface into components that are self-contained.

Chapter 5, Building a Photo Gallery App Using CollectionView and CarouselView, details how Xamarin.Forms 4 introduces CollectionView and CarouselView. In this chapter, we will use them to build a photo gallery app to learn how to master the controls.

Chapter 6,Building a Location Tracking App Using GPS and Maps, taps into the use of geolocation data from the device's GPS and how to plot this data on a layer on a map. It also explains how to use background services to keep tracking the location over a long period of time to create a heat map of where you spend your time.

Chapter 7,Building a Weather App for Multiple Form Factors, is all about consuming a third-party REST interface and displaying the data in a user-friendly way. We will hook up to a weather service to get the forecast for the current location you are in and display the results in a list.

Chapter 8,Setting Up a Backend for a Chat App Using Azure Services, is the first of a two-part chapter in which we'll set up a chat app. This chapter explains how to use Azure Services to create a backend that exposes functionality through SignalR to set up a real-time communication channel between apps.

Chapter 9,Building a Real-Time Chat Application, follows on from the previous chapter and covers the frontend of the app, in this case, a Xamarin.Forms app that connects to the backend and that relays messages between users. The chapter focuses on setting up SignalR on the client side and explains how to create a service model that abstracts this communication through messages and events.

Chapter 10,Creating anAugmented RealityGame, ties the two different AR APIs into a single UrhoSharp solution. Android uses ARCore to handle augmented reality, and iOS uses ARKit to do the same. We will drop down into platform-specific APIs through custom renderers and expose the result as a common API for the Xamarin.Forms app to consume.

Chapter 11,Hot Dog or Not Hot Dog Using Machine Learning, covers the creation of an app that uses machine learning to identify whether an image contains a hot dog or not.

To get the most out of this book

We recommend that you read the first chapter to make sure that you are up to speed with the basic concepts of Xamarin in general. After that, you could pretty much pick any chapter you would like to learn more about. Each chapter is standalone but the chapters are ordered by complexity; the further you are into the book, the more complex the app will be.

The apps are adapted for real-world use but some parts are left out, such as proper error handling and analytics, since they are out of the scope of the book. You should, however, get a good grasp of the building blocks of how to create an app.

Having said that, it does help if you have been a C# and .NET developer for a while, since many of the concepts are not really app-specific but are good practice in general, such as Model-View-ViewModel and Inversion of Control.

But, most of all, it's a book you can use to kick-start your Xamarin.Forms development learning curve by focusing on what chapters interest you the most.

If you are using the digital version of this book, we advise you to type the code yourself or access the code via the GitHub repository (link available in the next section). Doing so will help you avoid any potential errors related to the copying and pasting of code.

Download the example code files

You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packtpub.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packt.com.
2. Select the Support tab.
3. Click on Code Downloads.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub athttps://github.com/PacktPublishing/Xamarin.Forms-4-Projects.In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available athttps://github.com/PacktPublishing/. Check them out!

Download the color images

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: https://static.packt-cdn.com/downloads/9781839210051_ColorImages.pdf.

Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Mount the downloaded WebStorm-10*.dmg disk image file as another disk in your system."

A block of code is set as follows:

html, body, #map {
 height: 100%; 
 margin: 0;
 padding: 0
}

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

[default]
exten => s,1,Dial(Zap/1|30)
exten => s,2,Voicemail(u100)
exten => s,102,Voicemail(b100)
exten => i,1,Voicemail(s0)

Any command-line input or output is written as follows:

          $ mkdir css
          

          $ cd css
        

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Select System info from the Administration panel."

Get in touch

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