.NET MAUI Projects E-Book

Michael Cummings

• Herausgeber: Packt Publishing
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 638

Veröffentlichungsjahr: 2024

Beschreibung

This third edition of .NET MAUI Projects explores the features of .NET MAUI, a lightweight multi-platform development toolkit for building apps with a rich user interface. Updated to cover the latest features of .NET MAUI, including CollectionView and Shell, this book delves into concepts such as machine learning and cloud services.
Starting with an overview of .NET Core and how it works, this book shares tips for choosing the right development environment for planning multi-platform apps. You'll then build your first .NET MAUI app and advance to learning how to use Shell to implement app architecture. Progressing in complexity, the projects guide you through creating apps, ranging from a location tracker and weather map to machine learning and multiplayer games. Further, the book will take you through modern mobile development frameworks such as SQLite, .NET Core, and ML.NET, empowering you to customize your apps for Windows, macOS, Android, and iOS platforms for native-like performance. Engaging examples are woven throughout the book so you can grasp essential concepts by writing code rather than extensive theory.
By the end of this book, you'll be ready to develop your own native apps using .NET MAUI and associated technologies such as .NET Core, Visual Studio 2022, and C#.

Leseprobe

.NET MAUI Projects

Build multi-platform desktop and mobile apps from scratch using C# and Visual Studio 2022

Michael Cummings Daniel Hindrikes Johan Karlsson

.NET MAUI Projects

Copyright © 2024 Packt Publishing

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Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

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First published: December 2018

Second edition: June 2020

Third edition: February 2024

Production reference: 2080224

Published by Packt Publishing Ltd.

Grosvenor House

11 St Paul’s Square

Birmingham

B3 1RB, UK

ISBN 978-1-83763-491-0

www.packtpub.com

I dedicate this book to my rock, my confidant, and my partner for life, Rita. Your unwavering support and love have been my guiding light through thick and thin. This book is dedicated to you with all my heart.

– Michael Cummings

I dedicate this book to all the people I met during my years as a Xamarin developer who never believed in Xamarin. If you read this book, you will hopefully understand how great Xamarin is!

– Daniel Hindrikes

This book is dedicated to the spider in my basement that motivated me to write a book thick enough to finally kill it with.

– Johan Karlsson

Foreword

I’d never actually made a mobile app before, but that didn’t stop me from standing in line, a little starstruck, to get my hands on a preview edition of a Xamarin.Forms book –signed by the author! Microsoft Build 2015 was an amazing conference, but nothing topped the Xamarin afterparty, and getting to meet one of my favorite technical writers was unbelievable. I walked away from the party with an armful of little stuffed monkeys and my personally inscribed book.

I had no idea at the time that I’d be frantically reading that book a few months later to prepare for my interview with the Xamarin.Forms team. I had no idea at the time that I’d spend the next eight and a half years with them – first, building the framework, taking it from 1.5 to 5.0, and expanding from mobile to desktop, too; then, leading and growing the team; and finally, helping to architect the next evolution of cross-platform development with .NET MAUI, .NET for iOS, and .NET for Android.

The mobile and desktop development world changes quickly, and any framework must be ready to bend, shift, and grow along with its underlying platforms. .NET MAUI is meant to be as flexible as the palm trees that sway with island winds. With that goal comes a formidable challenge – how do we build a framework that will stay constant enough for developers to rely on, yet continue to be relevant with the modern landscape?

We use the word “evolution” a lot when we talk about .NET MAUI because that’s the most apt term for what it is. Each new version looks familiar – the fundamentals are all there – but if you dig a little deeper, you’ll see the new capabilities, boosted performance, and updated expectations that make each version unique. If we did our jobs right, each version will deliver more delight than the last.

I’ve had the pleasure of working with Michael for several years, and when I learned that he would be writing this book, I wasn’t surprised at all. Michael is a natural teacher, and he understands that .NET MAUI (and, of course, .NET for Android and .NET for iOS) is a sensible choice for the simplest of apps as well as more complex and intricate apps. This book walks you through the journey of your basic first app and onward to the real-world scenarios that you’re likely to incorporate in your next project.

And even though you can be sure that .NET MAUI, .NET for Android, and .NET for iOS will continue to evolve and that some of the code you find in this book will look a bit different a few years from now, you can also be sure that the concepts and the fundamentals you learn in this book will be valuable for a long time to come. Have some fun with this book, and keep coding!

Samantha Houts

Principal Group Engineering Manager – .NET MAUI/.NET for Android/.NET for iOS

Contributors

About the authors

Michael Cummings is a senior development engineer at Microsoft. He currently works on the Visual Studio tooling for building WPF, Xamarin.Forms, and .NET MAUI apps. He has experience as a developer and architect with a focus on app development, design, deployment, and the business process as it relates to technology. Michael has dabbled in graphics and game programming since the days of the TI99-4/A. He contributes to open source projects, including AXIOM, a .NET 3D rendering engine, and Planeshift, a 3D Massive Multiplayer Online Role-Playing Game (MMORPG). Michael lives in Lexington, MA, with his wife and their dog. When not working with technology, he enjoys watching movies, trying out new recipes, and the occasional game of full-contact racquetball.

I want to give a special thank you to my faithful companion, Smidgeon, who was always on point to be the needed distraction. You are missed.

Thank you to all the members of the teams I work with at Microsoft, for your patience and knowledge.

Additionally, thank you to the incredible team at Packt and the reviewers for this edition of the book, Pietro Libro and Robby Gunawan Sutanto; your comments and suggestions were invaluable.

Daniel Hindrikes is a developer and architect with a passion for developing mobile apps powered by the cloud. Daniel fell in love with Xamarin in the early days of Xamarin when he realized that he could use C# even for iOS and Android apps and that he could share code with the Windows apps he was also building. But Daniel started to build mobile apps long before that, working on Android apps with Java and even Java ME apps (a long, long time ago).

Daniel enjoys sharing his knowledge and can be found speaking at conferences, blogging, or recording the podcast The Code Behind. Daniel works at tretton37 in Sweden and has experience working with both local and global customers.

I want to say a special thanks to my family, my wife, Anna-Karin, and our twins, Ella and Willner, all of whom have supported me during the writing process.

I also would like to say thanks to the fantastic team at Packt and our technical reviewers, who helped us write this book and make us look better than we really are.

Johan Karlsson has been working with Xamarin since the days of MonoTouch and Mono for Android, and it all started with writing a game. He is a full stack developer, currently focusing on mobile applications using Xamarin, but has in the past worked a lot with ASP.NET MVC, Visual Basic .NET (not proud), and C# in general. Also, he’s created a whole bunch of databases in SQL Server over the years.

Johan works at tretton37 in Sweden and has about 20 years of experience in the trade of assembling ones and zeros.

I want to send a special thanks to my partner in life, Elin. Thanks for being there during this special period of time including (but not limited to) moving together, living through a pandemic, writing a book, and selling a house. And, of course, to my children, Ville and Lisa, for being an inspiration in life!

Also, thanks to Packt and our tech reviewers, who nitpicked our applications apart, making us spend late nights correcting our code.

About the reviewers

Pietro Libro is a seasoned technology enthusiast with over two decades of experience in software development. He has honed his practical problem-solving skills through engagements in public administration, finance, and the automation industries. Simultaneously pursuing university education and professional work, Pietro attained a second-level degree, enriching his practical knowledge. Demonstrating a commitment to continuous learning, he holds numerous certifications and actively imparts his expertise as a technical speaker. His areas of expertise span a diverse range of technologies, with a particular emphasis on software and cloud architecture. Born in Italy, Pietro moved to Switzerland in 2013 and currently works as a Cloud Solution Architect. He resides in Zürich with his wife, Eleonora, and daughter, Giulia.

Robby Gunawan is a proficient full stack C# developer specializing in Windows Forms applications. He has been actively involved in writing commercial software since 2007, contributing his skills to several companies in Indonesia. His journey began with Basic during high school, followed by VB6 in university, and subsequently transitioning to VB.NET. In his professional career, he has adeptly embraced C#. Leveraging his C# background, Robby successfully published his first mobile application for Windows Phone 7 and developed his initial Android application using Xamarin Forms. Beyond software development, he possesses additional expertise as a Windows Server Administrator, Postfix Administrator, and WordPress Designer and Administrator.

Table of Contents

Preface

Part 1: Introduction

1

Introduction to .NET MAUI

Defining native applications

.NET mobile

Code sharing

Use of existing knowledge

.NET mobile platforms

Exploring the .NET MAUI framework

The architecture of .NET MAUI

Defining a UI using XAML

.NET MAUI versus traditional .NET mobile

Setting up our development machine

Setting up a Mac

Setting up a Windows machine

.NET mobile productivity tooling

Xamarin Hot Restart

Hot Reload

Windows Subsystem for Android

Summary

2

Building Our First .NET MAUI App

Technical requirements

Project overview

Setting up the project

Creating the new project

Examining the files

Updating the .NET MAUI packages

Creating a repository and a TodoItem model

Defining a to-do list item

Creating a repository and its interface

Connecting SQLite to persist data

Using MVVM – creating views and ViewModels

Defining a ViewModel base class

Introducing the CommunityToolkit.Mvvm library’s ObservableObject and ObservableProperty

Creating MainViewModel

Creating TodoItemViewModel

Creating the ItemViewModel class

Creating the MainView view

Creating the ItemView view

Wiring up dependency injection

Making the app run

Adding data bindings

Navigating from MainView to ItemView to add a new item

Adding new items to the list

Binding ListView in MainView

Creating a ValueConverter object for the item’s status

Navigating to an item using a command

Marking an item as complete using a command

Creating the filter toggle function using a command

Laying out the contents

Setting an application-wide background color

Laying out the MainView and ListView items

Summary

3

Converting a Xamarin.Forms App into .NET MAUI

Technical requirements

Project overview

Migrating into a blank .NET MAUI template

Creating a new Xamarin.Forms app

Creating a new .NET MAUI app

Migrating the MauiMigration app to MyMauiApp

Manual migration overview

Converting the Xamarin.Forms projects from .NET Framework into .NET SDK style

Updating code from Xamarin.Forms to .NET MAUI

Updating any incompatible NuGet packages

Addressing any breaking API changes

Custom renderers and effects

Running the converted app and verifying its functionality

Installing and running .NET Upgrade Assistant

Installing .NET Upgrade Assistant

Preparing to run .NET Upgrade Assistant

Running .NET Upgrade Assistant

Summary

Part 2: Basic Projects

4

Building a News App Using .NET MAUI Shell

Technical requirements

Project overview

Building the news app

Setting up the project

Creating the structure of the app

Creating the news service

Wiring up the NewsService class

Handling navigation

Summary

5

A Matchmaking App with a Rich UX Using Animations

Technical requirements

Project overview

Creating the matchmaking app

Setting up the project

Creating the Swiper control

Testing the control

Wiring up the Swiper control

Summary

6

Building a Photo Gallery App Using CollectionView and CarouselView

Technical requirements

Project overview

Building the photo gallery app

Creating the new project

Importing photos

Creating the gallery view

Summary

7

Building a Location Tracking App Using GPS and Maps

Technical requirements

Project overview

Building the MeTracker app

Creating a repository to save the locations of the users

Creating a service for location tracking

Setting up the app logic

Background location tracking on iOS and Mac Catalyst

Background location tracking with Android

Creating a heat map

Creating a custom control for the map

Refreshing the map when the app resumes

Summary

8

Building a Weather App for Multiple Form Factors

Technical requirements

Project overview

Building the weather app

Creating models for the weather data

Creating a service to fetch the weather data

Configuring the application platforms so that they use location services

Creating the ViewModel class

Creating the view for tablets and desktop computers

Creating the view for phones

Adding services and ViewModels to dependency injection

Navigating to different views based on the form factor

Handling states with VisualStateManager

Summary

Part 3: Advanced Projects

9

Setting Up a Backend for a Game Using Azure Services

Technical requirements

Project overview

An overview of the game

Understanding the different Azure serverless services

Azure SignalR Service

Azure Functions

Building the serverless backend

Creating a SignalR service

Using Azure Functions as an API

Deploying the functions to Azure

Summary

10

Building a Real-Time Game

Technical requirements

Project overview

Getting started

An overview of the game

Building the game app

Creating the game services

Creating the Connect page

Creating the Lobby page

Creating the Match page

Testing the completed project

Summary

11

Building a Calculator Using .NET MAUI Blazor

Technical requirements

Project overview

What is Blazor?

Creating the calculator app

Setting up the project

Creating the Keypad view

Creating the Compute service

Adding memory functions

Resizing the main window

Summary

12

Hot Dog or Not Hot Dog Using Machine Learning

Technical requirements

Machine learning

Azure Cognitive Services – Custom Vision

Core ML

TensorFlow

ML.Net

The project overview

Getting started

Building the Hot Dog or Not Hot Dog application using machine learning

Training a model

Building the app

Summary

Index

Other Books You May Enjoy

Preface

.NET MAUI Projects is a hands-on book in which you get to create nine applications from the ground up. You will gain the fundamental skills you need to set up your environment, and we will explain what .NET Mobile is before we transition into .NET MAUI 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, upgrading from Xamarin.Forms, animations, consuming REST interfaces, real-time communication using SignalR, and location tracking using a device’s GPS. There is also room for machine learning, a touch of .NET Blazor, 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 .NET Mobile, and specifically .NET MAUI, to create applications using .NET and C#.

No knowledge of .NET Mobile is required in advance, but it would be a great help if you’ve worked with traditional .NET Mobile and want to take the step toward .NET MAUI.

What this book covers

Chapter 1, Introduction to .NET MAUI, explains the basic concepts of .NET Mobile and .NET MAUI. 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 .NET MAUI App, guides you through the concepts of Model-View-ViewModel (MVVM) and explains how to use the Inversion of Control pattern to simplify the creation of views and view models. We will create a to-do app that supports navigation, filtering, and the addition of to-do items to a list, and will also render a user interface that takes advantage of the powerful data-binding mechanisms in .NET MAUI.

Chapter 3, Converting a Xamarin.Forms App to .NET MAUI, walks through the steps to convert an existing Xamarin.Forms app running on Mono to a .NET MAUI app running on .NET 7. We will discuss two different methods for converting your Xamarin.Forms application to .NET MAUI. The first method will use a new .NET MAUI project and move our old Xamarin.Forms code into the new project, and the second method will use the .NET Upgrade Assistant tool to do some of the upgrades for us.

Chapter 4, Building a News App Using .NET MAUI Shell, explores the default navigation template in .NET MAUI, Shell, a standard way to define the structure of .NET MAUI apps. In this chapter, you will learn all you need to know to use Shell in a .NET MAUI app.

Chapter 5, 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 self-contained components.

Chapter 6, Building a Photo Gallery App Using CollectionView and CarouselView, details the .NET MAUI CollectionView and CarouselView controls. In this chapter, we will use them to build a photo gallery app to learn how to master the controls.

Chapter 7, 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 8, 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 9, Setting Up a Backend for a Game Using Azure Services, is the first of two parts in which we’ll set up a game 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 10, Building a Real-Time Game, follows on from the previous chapter and covers the frontend of the app – in this case, a .NET MAUI app that connects to the backend and 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 11, Building a Calculator Using .NET MAUI Blazor, explores a .NET Blazor app embedded within a .NET MAUI app. We will write part of the calculator app using Blazor and host that in .NET MAUI using BlazorWebView. We will also communicate between Blazor and .NET MAUI.

Chapter 12, 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. However, you should 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 MVVM and Inversion of Control.

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

Software/Hardware covered in the book

OS requirements

Visual Studio Community Edition. A computer capable of running Windows 10 or later for UWP and Android. A Mac that is capable of running macOS Mojave 10.14 to use the iOS simulator

Windows 10 or later, macOS Sierra 10.12 or later

Xcode. A Mac that is capable of running macOS Sierra 10.14

macOS Mojave 10.14

If you are using the digital version of this book, we advise you to type the code yourself or access the code from the book’s GitHub repository (a link is 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 GitHub at https://github.com/PacktPublishing/MAUI-Projects-3rd-Edition. If there’s an update to the code, it will be updated in the GitHub repository.

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

Conventions used

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

Code in text: 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: “Since all .NET MAUI programs start with the MauiProgram.cs file, that seems like a good place to start.”

A block of code is set as follows:

.keypad {     width: 300px;     margin: auto;     margin-top: -1.1em; }

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

    builder.Services.AddMauiBlazorWebView(); #if DEBUG     builder.Services.AddBlazorWebViewDeveloperTools();     builder.Logging.AddDebug(); #endif

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

$ mkdir ViewModels $ cd ViewModels

Bold: Indicates a new term, an important word, or words that you see onscreen. For instance, words in menus or dialog boxes appear in bold. Here is an example: “Open Visual Studio 2022 and select Create a new project.”

Tips or important notes

Appear like this.

Get in touch

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Part 1: Introduction

In this part, you will get an overview of .NET MAUI and learn how to install .NET MAUI in order to create your first .NET MAUI project. As you create your first projects, you will learn about the Model-View-ViewModel design pattern and how to use it in .NET MAUI apps. Xamarin users will also learn how to upgrade their projects to .NET MAUI either manually or by using the .NET Upgrade Assistant.

This part has the following chapters:

Chapter 1, Introduction to .NET MAUIChapter 2, Building Your First .NET MAUI AppChapter 3, Converting a Xamarin.Forms App to .NET MAUI