Introducing
.NET MAUI
Build and Deploy Cross-platform
Applications Using C# and .NET
Multi-platform App UI
—
Shaun Lawrence
Introducing
.NET MAUI
Build and Deploy
Cross-platform Applications
Using C# and .NET
Multi-platform App UI
Shaun Lawrence
Introducing .NET MAUI: Build and Deploy Cross-platform Applications Using C# and .NET Multi-platform App UI
Shaun Lawrence
St Ives, UK
ISBN-13 (pbk): 978-1-4842-9233-4\ |
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ISBN-13 (electronic): 978-1-4842-9234-1 |
https://doi.org/10.1007/978-1-4842-9234-1 |
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Copyright © 2023 by Shaun Lawrence
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Table of Contents
About the Author\ xv
About the Technical Reviewer\ xvii
Acknowledgments\ xix
Introduction\ xxi
Part I: Getting to Know .NET MAUI\ 1
Chapter 1: Introduction to .NET MAUI\ 3
What is .NET MAUI?\ 3 Digging a Bit Deeper 5 Where Did It Come From? 6 How It Differs From the Competition\ 7 Why Use .NET MAUI? 8 Supported Platforms 8 Code Sharing\ 9 Developer Freedom\ 10 Community\ 10 Fast Development Cycle\ 10 Performance 11 Strong Commercial Offerings\ 12
iii
Table of Contents
Limitations of .NET MAUI\ 13 No Web Assembly (WASM) Support\ 13 No Camera API 13 Apps Won’t Look Identical on Each Platform\ 14 Lack of Media Playback Out of the Box\ 14
The Glass Is Half Full, Though\ 14 How to Build .NET MAUI Applications 15 Visual Studio 15 Summary\ 17
Chapter 2: Building Our First application\ 19
Setting Up Your Environment\ 19 macOS\ 19 Windows\ 27 Visual Studio to macOS\ 28 Troubleshooting Installation Issues 32
.NET MAUI Workload Is Missing 32 Creating Your First Application\ 33 Creating in Visual Studio\ 33 Creating in the Command Line\ 37 Building and Running Your First Application\ 38 Getting to Know Your Application\ 41 WidgetBoard\ 41 Summary\ 42 Source Code\ 43
iv
Table of Contents
Chapter 3: The Fundamentals of .NET MAUI\ 45
Project Structure 45 /Platforms/ Folder 48 /Resources/ Folder\ 51 Where To Begin?\ 56 Generic Host Builder\ 56 What Is Dependency Injection?\ 57 Registering Dependencies 60 Application Lifecycle\ 62 Application States\ 62 Lifecycle Events 64 Handling Lifecycle Events 65 Cross-Platform Mappings to Platform Lifecycle Events\ 66 Platform-Specific Lifecycle Events 67 Summary\ 72
Chapter 4: An Architecture to Suit You\ 75
A Measuring Stick 75 Prerequisites\ 76 Model View ViewModel (MVVM)\ 77 Model 78 View 79 ViewModel\ 80 Model View Update (MVU)\ 83 Getting Started with Comet\ 84 Adding Your MVU Implementation\ 84
v
Table of Contents
XAML vs. C# Markup\ 86 Plain C#\ 87 C# Markup\ 88 Chosen Architecture for This Book 89 Adding the ViewModels\ 90 Adding Views\ 96 Viewing Your Widget\ 99 MVVM Enhancements 101 Summary\ 105 Source Code\ 107
Part II: User Interface\ 109
Chapter 5: User Interface Essentials\ 111
Prerequisites\ 111
Models 111
Pages 113
ViewModels\ 114
App Icons\ 116
Adding Your Own Icon 116
Platform Differences 117
Splash Screen\ 118
XAML 119
Dissecting a XAML File\ 120
Building Your First XAML Page\ 122
Layouts\ 124
AbsoluteLayout\ 124
FlexLayout\ 126
Grid\ 128
HorizontalStackLayout 131
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Table of Contents
VerticalStackLayout 132 Data Binding\ 135 Binding\ 136 Applying the Remaining Bindings 140 MultiBinding\ 141 Command\ 144 Compiled Bindings 147 Shell\ 148 ShellContent\ 149 Navigation\ 150 Flyout 154 Tabs\ 160 Search\ 160 Taking Your Application for a Spin 161 Summary\ 163 Source Code\ 164 Extra Assignment\ 164
Chapter 6: Creating Our Own Layout\ 165
Placeholder\ 166 ILayoutManager\ 168 BoardLayout\ 169 BoardLayout.xaml 169 BoardLayout.xaml.cs\ 172 FixedLayoutManager 177 Accepting the Number of Rows and Columns for a Board\ 179 Providing Tap/Click Support Through a Command\ 181 Building the Board Layout\ 182 Setting the Correct Row/Column Position for Each Widget\ 185
vii
Table of Contents
Using Your Layout\ 187
Adding a Factory That Will Create Instances of Your Widgets\ 187
WidgetTemplateSelector 193
Updating FixedBoardPageViewModel 194
Finally Using the Layout\ 196
Summary\ 197
Source Code\ 198
Extra Assignment\ 198
Chapter 7: Accessibility 199
What Is Accessibility?\ 199 Why Make Your Applications Accessible?\ 200 What to Consider When Making Your Applications Accessible 200 How to Make Your Application Accessible\ 201 Screen Reader Support\ 201 Suitable Contrast\ 208 Dynamic Text Sizing 210 Testing Your Application’s Accessibility 215 Android\ 215 iOS\ 215 macOS\ 216 Windows\ 216 Accessibility Checklist\ 216 Summary\ 218 Source Code\ 219 Extra Assignment\ 219
viii
Table of Contents
Chapter 8: Advanced UI Concepts 221
Adding the Ability to Add a Widget to a Board 221
Possible Ways of Achieving Your Goal\ 222
The Chosen Approach 224
Styling\ 230
Examining the Default Styles 232
Creating a Style\ 234
AppThemeBinding\ 236
Further Reading 236
Triggers\ 237
Creating a DataTrigger 238
EnterActions and ExitActions 239
Creating a TriggerAction\ 240
Further Reading 242
Animations 242
Basic Animations\ 243
Combining Basic Animations\ 245
Cancelling Animations\ 246
Easings\ 246
Complex Animations\ 247
Combining Triggers and Animations\ 252
Summary\ 254
Source Code\ 255
Extra Assignment\ 255
Animate the BoxView Overlay 255
Animate the New Widget\ 255
ix
Table of Contents
Part III: Behind the Scenes\ 257
Chapter 9: Local Data\ 259
What Is Local Data?\ 259 File System\ 260 Cache Directory\ 260 App Data Directory\ 261 Database\ 261 Repository Pattern 262 SQLite\ 270 LiteDB\ 278 Database Summary\ 285 Application Settings (Preferences) 285 What Can Be Stored in Preferences?\ 286 Setting a Value in Preferences\ 286 Getting a Value in Preferences\ 288 Checking if a Key Exists in Preferences\ 290 Removing a Preference\ 291 Secure Storage\ 291 Storing a Value Securely 291 Reading a Secure Value 292 Removing a Secure Value\ 292 Platform specifics 293 Viewing the Result\ 295 Summary\ 296 Source Code\ 297 Extra Assignment\ 297
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Table of Contents
Chapter 10: Remote Data 299
What Is Remote Data?\ 299 Considerations When Handling Remote Data\ 300 Webservices 302 The Open Weather API\ 302 Adding Some State\ 319 Simplifying Webservice Access\ 326 Prebuilt Libraries\ 327 Code Generation Libraries\ 327 Further Reading\ 329 Polly 329 StateContainer from CommunityToolkit.Maui 330 Summary\ 330 Source Code\ 331 Extra Assignment\ 331 TODO Widget 331 Quote of the Day Widget\ 332 NASA Space Image of the Day Widget 332
Part IV: Utilizing the platforms\ 333
Chapter 11: Getting Specific\ 335
.NET MAUI Essentials\ 335
Permissions 336
Using the Geolocation API 341
Configuring Platform-Specific Components\ 346
Platform-Specific API Access 352
Platform-Specific Code with Compiler Directives\ 352
Platform-Specific Code in Platform Folders\ 354
xi
Table of Contents
Overriding the Platform-Specific UI\ 355
OnPlatform\ 355
Handlers\ 358
Summary\ 361
Source Code\ 362
Extra Assignment\ 362
Barometer Widget 362
Geocoding Lookup\ 363
Chapter 12: Testing 365
Unit Testing\ 365 Unit Testing in .NET MAUI\ 366 Adding Your Own Unit Tests 368 Testing Your View Models\ 372 Testing Asynchronous Operations\ 374 Testing Your Views 380
Device Testing\ 382 Creating a Device Test Project 383 Adding a Device-Specific Test\ 383 Running Device-Specific Tests\ 384 Snapshot Testing 386 Snapshot Testing Your Application 387 Passing Thoughts\ 390 Looking to the Future 390 Summary\ 391 Source Code\ 391
xii
Table of Contents
Chapter 13: Lets Get Graphical\ 393
.NET MAUI Graphics\ 393 Drawing on the Screen\ 394 Further Reading 397 Building a Sketch Widget\ 397 Creating the SketchWidgetViewModel\ 397 Representing a User Interaction\ 398 Creating the SketchWidgetView\ 399 Registering Your Widget\ 404 Taking Your Widget for a Test Draw\ 404 Summary\ 405 Source Code\ 405 Extra Assignment\ 406
Part V: Finishing Our Application 407
Chapter 14: Releasing Our Application 409
Distributing Your Application\ 409 Android\ 410 iOS\ 412 macOS\ 415 Windows\ 416
Things to Consider\ 416 Following Good Practices\ 416 Performance 418 Linking 421 Crashes/Analytics 422 Obfuscation\ 424
Distributing Test Versions 426 Summary\ 427 xiii
Table of Contents
Chapter 15: Conclusion 429
Looking at the Final Product\ 429
Taking the Project Further\ 431
Useful Resources\ 432
StackOverflow\ 433
GitHub 433
YouTube\ 433
Social Media\ 434
Yet More Goodness 434
Looking Forward\ 434
Upgrading from Xamarin.Forms\ 435
Comet\ 435
Testing\ 436
Index 437
xiv