Flutter App Development: How to write for IOS and Android at once

Worldwide Praise for Flutter App Development: How to Write for iOS and Android at Once....5 Table of Contents....7 About the Author....16 About the Technical Reviewer....17 Who Is This Book For?....18 Foreword....23 Preface....25 Chapter 1: Hello Flutter....27 What Is Flutter?....28 Why Flutter?....29 The Other Options....30 Native Solutions....31 Conclusion....32 Chapter 2: Developing in Flutter....33 The Flutter Toolchain....34 The Flutter SDK....34 Installing the Flutter SDK....34 IDEs....34 VS Code from Microsoft....35 Android Studio/IntelliJ from JetBrains....35 Which IDE Should I Use?....35 IDE DevTools....36 Emulators....37 iOS Simulator....37 Android Emulator....38 Keeping the Tools Up to Date....39 Flutter doctor....40 Flutter Upgrade....41 The Flutter Development Process....42 Scaffolding the App and Files....43 Anatomy of a Flutter Project....43 Running Your App....45 Running It As a Web App....46 Running It on a Tethered Device....47 Hot Reloading....47 Debugging....48 Conclusion....49 Chapter 3: Everything Is Widgets....50 UI As Code....53 Built-In Flutter Widgets....54 Value Widgets....55 Layout Widgets....56 Navigation Widgets....56 Other Widgets....57 How to Create Your Own Stateless Widgets....57 Widgets Have Keys....61 Passing a Value into Your Widget....62 Stateless and Stateful Widgets....64 So Which One Should I Create?....64 Conclusion....65 Chapter 4: Value Widgets....66 The Text Widget....66 The Icon Widget....67 The Image Widget....69 Embedded Images....70 Network Images....71 Sizing an Image....71 SnackBar Widget....74 Input Widgets....76 Text Fields....77 Making Your TextField Fancy....77 Password Boxes....78 Adjusting the Soft Keyboard....79 Restricting the Data That Can Be Typed....80 Checkboxes....81 Radio Buttons....82 Sliders....84 Dropdowns....85 Putting the Form Widgets Together....87 Form Widget....87 FormField Widget....89 TextFormField and DropdownButtonFormField....90 onSaved....91 validator....91 Submitting the Form....92 One Big Form Example....93 Conclusion....93 Chapter 5: Responding to Gestures....94 Meet the Button Family....95 ElevatedButton....97 TextButton and IconButton....97 FloatingActionButton (FAB)....97 SegmentedButton....98 CupertinoButton....99 Dismissible....99 Custom Gestures for Your Custom Widgets....100 Step 1: Decide on Your Gestures and Behaviors....101 Step 2: Create Your Custom Widget....101 Step 3: Add a GestureDetector widget....102 Step 4: Associate Your Gesture with Its Behavior....103 Example 1: Reacting to a Long Press....103 Example 2: Pinching to Add a New Item....105 Example 3: Swiping Left or Right....106 Conclusion....108 Chapter 6: Navigation and Routing....109 Stack Navigation....110 Navigating Forward and Back....111 Using Anonymous Routes....112 Get Result After a Scene Is Closed....113 Drawer Navigation....114 The Drawer Widget....115 Filling the Drawer....117 Tab Navigation....119 DefaultTabController....120 TabBarView....121 TabBar and Tabs....121 TabBar at the Bottom....122 The Dialog Widget....123 showDialog() and AlertDialog....124 Responses with a Dialog....125 Navigation Methods Can Be Combined....126 Chapter 7: Managing State....128 What Is State?....128 The Shape of a StatefulWidget....130 The Most Important Rule About State!....131 Passing State Down....132 Lifting State Back Up....133 An Example of State Management....135 When Should We Use State?....139 Conclusion....141 Chapter 8: State Management Libraries....142 The InheritedWidget....142 The BLoC Pattern....143 Some Libraries....144 ScopedModel....144 Redux and Hooks....145 Provider....145 Whoa! That’s a Lot of Packages!....145 Raw State....146 Riverpod....147 1. Install flutter_riverpod....148 2. Wrap Your App with a ProviderScope....148 3. Write a Provider....149 Wait, What Is This Provider You Speak Of?....149 4. Inherit from ConsumerStateWidget....149 5. Read Data with ref.watch()....150 6. Write Data with ref.read()....151 Conclusion....151 Chapter 9: Making RESTful API Calls with HTTP....152 What Is an API Call?....153 The Flavors of API Requests....154 Making an HTTP GET or DELETE Request....155 Making an HTTP PUT, POST, or PATCH Request....157 HTTP Responses to Widgets....158 Brute Force – The Easy Way....158 FutureBuilder – The Clean Way....159 StreamBuilder....161 Strongly Typed Classes....163 Create a Business Class....163 Write a .fromJSON() Method....164 Use .fromJSON() to Hydrate the Object....164 One Big Example....165 Overview of the App....166 Create the Flutter App....168 Making a Strongly Typed Business Class....169 list_people.dart....170 A GET Request in Flutter....173 A DELETE Request in Flutter....173 upsert_person.dart....174 A POST and PUT Request in Flutter....175 Conclusion....176 Chapter 10: Styling with Themes....177 Thinking in Flutter Styles....177 Individual Styles....178 Styling Text....178 Mass-Changing Values....180 Themes....181 1. ColorScheme....182 2. TextTheme....186 3. Widget-Specific Themes....188 4. Put Them Together in a Theme....189 5. Override the Styles on Individual Widgets....190 Final Styling Thoughts....191 A Word About Colors....191 Custom Fonts....193 Conclusion....196 Chapter 11: Laying Out Your Widgets....198 Our Approach....198 1. Layout the Entire Screen (a.k.a. Scene)....199 2. Position Widgets Above and Below Each Other or Side by Side....199 3. Handle Situations When We Run Out of Space and Overflow the Scene....201 4. Handle Extra Space in the Scene....201 5. Make Finer Adjustments in Positioning....202 Laying Out the Whole Scene....202 MaterialApp Widget....203 The Scaffold Widget....204 The AppBar Widget....206 SafeArea Widget....207 Flutter’s Layout Algorithm....208 The Dreaded “Unbounded Height” Error....208 The Algorithm Itself....212 Conclusion....215 Chapter 12: Layout – Positioning Widgets....216 Putting Widgets Next to or Below Others....216 Responsive Design....218 Responsive Design in Flutter....218 Flex and MediaQuery....219 Conclusion....220 Chapter 13: Layout – Fixing Overflows....221 Overflow Warning Bars....221 Our Options to Correct Overflows....222 A Sample Problem to Solve....223 1. Allow the Children to Wrap....225 2. Squeeze the Children Until They Fit....226 3. Allow the User to Scroll....228 SingleChildScrollView Widget....229 The ListView Widget....231 ListView Is Memory Efficient....231 ListView Is Very Flexible....232 Regular ListView....233 ListView.builder: When You’re Building Widgets from a List of Objects....233 GridView Widget....234 GridView.extent()....235 GridView.count()....236 Conclusion....238 Chapter 14: Layout – Filling Extra Space....239 What if There’s Extra Space Left Over?....240 mainAxisAlignment....240 crossAxisAlignment....242 IntrinsicWidth....243 Expanded Widget....244 Open Space with Expandeds....247 Conclusion....248 Chapter 15: Layout – Fine-Tuning Positioning....249 Container Widget and the Box Model....250 EdgeInsets for Padding and Margin....251 Alignment and Positioning Within a Container....252 Container Sizes Are Not Obvious....254 Container Decorations....256 Border....259 BorderRadius....260 BoxShape....262 Conclusion....264 Chapter 16: Layout – Special Presentation Widgets....265 Slivers....265 Stack Widget....266 Positioned Widget....268 Card Widget....270 The Table Widget....271 Conclusion....274 Appendix A: Dart Language Overview....275 What Is Dart?....275 Expected Features – Dart Cheat Sheet....276 Data Types....276 Arrays/Lists....277 Conditional Expressions....277 Looping....278 Classes....278 Class Constructors....279 Unexpected Things About Dart....279 Type Inference....279 final vs. const....280 Null Safety....281 String interpolationwith $....282 Multiline Strings....282 Spread Operator....283 Map....283 Functions Are Objects....283 Big Arrow/Fat Arrow/Lambda....284 Named Function Parameters....284 Omitting “new” and “this.”....285 Class Constructor Parameter Shorthand....286 Private Class Members....287 Mixins....287 The Cascade Operator (..)....288 No Overloading....289 Named Constructors....289 Appendix B: Futures, Async, and Await....291 Flutter Apps Use an Event Loop....291 Why Would It Wait?....292 How Do We Get the Data from a Future?....293 Await....294 Async....295 Summary....296 Appendix C: Including Packages in Your Flutter App....297 Finding a Library to Use....297 Downloading the Library....299 The pubspec.yaml File....300 Using These Packages in Your Code....301 Keeping Your Packages Current....302 How to Upload Your Own Library....303 Appendix D: How to Work with Files....306 Including a File with Your App....307 Writing a File....308 And Reading It!....309 Using JSON....310 Writing Your App’s Memory to JSON....311 Reading JSON into Your App’s Memory....312 Shared Preferences....313 To Write Preferences....314 To Read Preferences....314 Conclusion....315 Appendix E: How to Debug Your Layout....316 Index....320