# šŸ“š Official Books **URL:** https://forums.kodeco.com/c/books/6.md?page=37 [Latest](https://forums.kodeco.com/latest.md) Ā· [Categories](https://forums.kodeco.com/categories.md) Ā· [Tags](https://forums.kodeco.com/tags.md) **Page:** 38 --- ## [What is an AR app?](https://forums.kodeco.com/t/what-is-an-ar-app/156704)
**Author:** [@alice7890](https://forums.kodeco.com/u/alice7890)\ **Replies:** 0\ **Last updated:** [November 11, 2021, 11:51am UTC](https://forums.kodeco.com/t/what-is-an-ar-app/156704 "2021-11-11T11:51:05Z")
AR apps are simply augmented reality apps that utilize AR technology for showcasing their products. For example, if you own an e-commerce website, then you will develop an AR app for people to visualize the products in ā€¦ --- ## [Chapter 12, ResourceType, where keyword](https://forums.kodeco.com/t/chapter-12-resourcetype-where-keyword/156386)
**Author:** [@dreadbot](https://forums.kodeco.com/u/dreadbot)\ **Replies:** 1\ **Last updated:** [November 11, 2021, 9:43am UTC](https://forums.kodeco.com/t/chapter-12-resourcetype-where-keyword/156386 "2021-11-11T09:43:03Z")
In the following code in Chapter 12, can someone explain the where keyword? Is this used specifically with generic types? Is this saying "where the ResourceType conforms to Codable? So is this saying the struct parameterā€¦ --- ## [Suggestion for Chapter 15](https://forums.kodeco.com/t/suggestion-for-chapter-15/156661)
**Author:** [@cyeh1234](https://forums.kodeco.com/u/cyeh1234)\ **Replies:** 0\ **Last updated:** [November 11, 2021, 1:28am UTC](https://forums.kodeco.com/t/suggestion-for-chapter-15/156661 "2021-11-11T01:28:10Z")
Just a suggestion for Chapter 15 Reading assignment for Nov. 10: chapter 9 & 15 Reading assignment for Nov. 17: chapter 10 & 11 Since I havenā€™t read 11 before reading 15, it would be nice for the Note to refer to Chapā€¦ --- ## [How to downgrade or uninstall the Android Emulator](https://forums.kodeco.com/t/how-to-downgrade-or-uninstall-the-android-emulator/156647)
**Author:** [@gncov101](https://forums.kodeco.com/u/gncov101)\ **Replies:** 0\ **Last updated:** [November 11, 2021, 12:21am UTC](https://forums.kodeco.com/t/how-to-downgrade-or-uninstall-the-android-emulator/156647 "2021-11-11T00:21:32Z")
HI, I clicked on an update to Android Studio Arctic Fox 2020 Patch 3 and then my emulator wonā€™t run. It gets a symbol not found error. From what I can tell on searching this issue, it seems I may need to go back to theā€¦ --- ## [Chapter 4: Can't find static text with display identifier](https://forums.kodeco.com/t/chapter-4-cant-find-static-text-with-display-identifier/156538)
**Author:** [@joseines](https://forums.kodeco.com/u/joseines)\ **Replies:** 2\ **Last updated:** [November 10, 2021, 4:45pm UTC](https://forums.kodeco.com/t/chapter-4-cant-find-static-text-with-display-identifier/156538 "2021-11-10T16:45:08Z")
Iā€™m getting a failed to get matching snapshot for the display text. Iā€™m using .accessibilityIdentifier(ā€œdisplayā€) for the Text, as the .accessibility(identifier:) function is deprecated. Donā€™t really know how to debug tā€¦ --- ## [Ch-15: Problem using moor\_generator](https://forums.kodeco.com/t/ch-15-problem-using-moor-generator/155792)
**Author:** [@mumin-a](https://forums.kodeco.com/u/mumin-a)\ **Replies:** 2\ **Last updated:** [November 10, 2021, 3:42pm UTC](https://forums.kodeco.com/t/ch-15-problem-using-moor-generator/155792 "2021-11-10T15:42:47Z")
I am having this error when trying to use moor\_genarator: \`/C:/flutter/.pub-cache/hosted/pub.dartlang.org/moor\_generator-4.4.1/lib/src/writer/database\_writer.dart:4:8: Error: Error when reading '/C:/flutter/.pub-cache/hā€¦ --- ## [Chapter 6 - Grocery Tile Fix](https://forums.kodeco.com/t/chapter-6-grocery-tile-fix/154855)
**Author:** [@mayank9018](https://forums.kodeco.com/u/mayank9018)\ **Replies:** 12\ **Last updated:** [November 10, 2021, 2:49pm UTC](https://forums.kodeco.com/t/chapter-6-grocery-tile-fix/154855 "2021-11-10T14:49:56Z")
Under ā€˜Finishing GroceryTileā€™ in chapter 6, using MainAxisAlignment.spaceBetween adds space between Container(used for color coding) and SizedBox as well making the GroceryTile look like this: Therfore, to fix this inā€¦ --- ## [8.6: AppLink class errata ... constants prefixed with "k"](https://forums.kodeco.com/t/8-6-applink-class-errata-constants-prefixed-with-k/155721)
**Author:** [@jefff9511](https://forums.kodeco.com/u/jefff9511)\ **Replies:** 5\ **Last updated:** [November 10, 2021, 2:44pm UTC](https://forums.kodeco.com/t/8-6-applink-class-errata-constants-prefixed-with-k/155721 "2021-11-10T14:44:00Z")
The AppLink class uses constants prefixed with k which I believe is deprecated. In the next version of the book, I guess there names should be changed. --- ## [How can I make endless scrolling background down?](https://forums.kodeco.com/t/how-can-i-make-endless-scrolling-background-down/40627)
**Author:** [@misterdave](https://forums.kodeco.com/u/misterdave)\ **Replies:** 1\ **Last updated:** [March 22, 2018, 11:11am UTC](https://forums.kodeco.com/t/how-can-i-make-endless-scrolling-background-down/40627 "2018-03-22T11:11:44Z")
I am learning chapter 15 ā€˜Making Drop Chargeā€™ And in this chapter we made an endless scrolling background going up.How can I make the same scrolling background but it will scroll down instead scroll up? --- ## [How to obtain the iPad system version macro definition identifier](https://forums.kodeco.com/t/how-to-obtain-the-ipad-system-version-macro-definition-identifier/156559)
**Author:** [@richmond\_jam](https://forums.kodeco.com/u/richmond_jam)\ **Replies:** 0\ **Last updated:** [November 10, 2021, 6:42am UTC](https://forums.kodeco.com/t/how-to-obtain-the-ipad-system-version-macro-definition-identifier/156559 "2021-11-10T06:42:33Z")
This week I need to finish logic for iPad. I want to obtain the iPad system version macro definition identifier. For example, we always use ā€œ\_\_IPHONE\_OS\_VERSION\_MAX\_ALLOWED \> \_\_IPHONE\_12\_0ā€ in iOS for iPhone. But now I wā€¦ --- ## [Patches with more control points? (biquadratic, bicubic, etc)](https://forums.kodeco.com/t/patches-with-more-control-points-biquadratic-bicubic-etc/156499)
**Author:** [@rnikander](https://forums.kodeco.com/u/rnikander)\ **Replies:** 3\ **Last updated:** [November 10, 2021, 3:17am UTC](https://forums.kodeco.com/t/patches-with-more-control-points-biquadratic-bicubic-etc/156499 "2021-11-10T03:17:40Z")
The book mentions this briefly in chapter 11: A patch consists of a certain number of control points, generally: bilinear: Four control points, one at each corner biquadratic: Nine control points bicubic: Sixteen conā€¦ --- ## [Stuck at chapter 2](https://forums.kodeco.com/t/stuck-at-chapter-2/153529)
**Author:** [@iadanish](https://forums.kodeco.com/u/iadanish)\ **Replies:** 5\ **Last updated:** [November 10, 2021, 12:06am UTC](https://forums.kodeco.com/t/stuck-at-chapter-2/153529 "2021-11-10T00:06:55Z")
Hi, I am unable to create a recipe app, is there anyone having video on book and how I can get started with chapter 2 --- ## [Chapter 7 - Nullability - Source Code is not null safe](https://forums.kodeco.com/t/chapter-7-nullability-source-code-is-not-null-safe/156332)
**Author:** [@dionv](https://forums.kodeco.com/u/dionv)\ **Replies:** 4\ **Last updated:** [November 9, 2021, 11:32pm UTC](https://forums.kodeco.com/t/chapter-7-nullability-source-code-is-not-null-safe/156332 "2021-11-09T23:32:40Z")
Ironicially, the source code for Chapter 7 does not appear to use Dart 2.12.0 or higher, therefore it is not null safe by default, which could confuse folks. So, if you hit this chapter, and are using the supplementayr ā€¦ --- ## [I don't understand "#keyPath()"](https://forums.kodeco.com/t/i-dont-understand-keypath/156406)
**Author:** [@pavedwalden](https://forums.kodeco.com/u/pavedwalden)\ **Replies:** 2\ **Last updated:** [November 9, 2021, 8:20pm UTC](https://forums.kodeco.com/t/i-dont-understand-keypath/156406 "2021-11-09T20:20:06Z")
In Chapter 2, there are two uses of what appears to be a function called ā€œ#keyPathā€ NSPredicate(format: "%K = %@", argumentArray: \[#keyPath(BowTie.searchKey), ... \]) these are the only instances of the string ā€œkeyPathā€ā€¦ --- ## [supplementary materials for this book](https://forums.kodeco.com/t/supplementary-materials-for-this-book/156242)
**Author:** [@maximko](https://forums.kodeco.com/u/maximko)\ **Replies:** 2\ **Last updated:** [November 9, 2021, 2:53pm UTC](https://forums.kodeco.com/t/supplementary-materials-for-this-book/156242 "2021-11-09T14:53:00Z")
Good day! In challenges itā€™s written ā€˜ā€˜solutions are available with the supplementary materials for this book if you get stuckā€™ā€™ but I canā€™t see any at the end of the book. Is it a separate file? Thank you. --- ## [State Management (Abstract class)](https://forums.kodeco.com/t/state-management-abstract-class/156439)
**Author:** [@olivaxa](https://forums.kodeco.com/u/olivaxa)\ **Replies:** 0\ **Last updated:** [November 9, 2021, 8:35am UTC](https://forums.kodeco.com/t/state-management-abstract-class/156439 "2021-11-09T08:35:22Z")
Hi. Can you help me please ? I would like to know : Abstract class leaves the implementation to subclass. Code will be safe, honestā€¦ Why exactly ? A subclass implements an abstract class. Why donā€™t we use class Meā€¦ --- ## [Flutter Resources](https://forums.kodeco.com/t/flutter-resources/156432)
**Author:** [@elasto](https://forums.kodeco.com/u/elasto)\ **Replies:** 0\ **Last updated:** [November 9, 2021, 7:59am UTC](https://forums.kodeco.com/t/flutter-resources/156432 "2021-11-09T07:59:45Z")
List of awesome Flutter resources here: https://github.com/Solido/awesome-flutter --- ## [AppBar text not seen in light mode](https://forums.kodeco.com/t/appbar-text-not-seen-in-light-mode/155938)
**Author:** [@ozkayas](https://forums.kodeco.com/u/ozkayas)\ **Replies:** 7\ **Last updated:** [November 9, 2021, 6:00am UTC](https://forums.kodeco.com/t/appbar-text-not-seen-in-light-mode/155938 "2021-11-09T06:00:44Z")
Hi, I ve just realized that the text and back icon of AppBar is white, so not visible on my app. The code in the theme file looks ok: I tried chaning foreground color to something else, but UI does not care ā€¦ --- ## [ThemeData for RecipeApp](https://forums.kodeco.com/t/themedata-for-recipeapp/153908)
**Author:** [@carlstep333](https://forums.kodeco.com/u/carlstep333)\ **Replies:** 5\ **Last updated:** [November 9, 2021, 4:48am UTC](https://forums.kodeco.com/t/themedata-for-recipeapp/153908 "2021-11-09T04:48:04Z")
Hey, hope someone can help. Iā€™ve been working through the first section of Flutter Apprentice and created the Recipe App. I followed the instructions and created the app, everything worked fine except for the Theme. Theā€¦ --- ## [Unsupported metadata version. Check that your Kotlin version is \>= 1.0: java.lang.IllegalStateException: Unsupported metadata version. Check that your Kotlin version is \>= 1.0](https://forums.kodeco.com/t/unsupported-metadata-version-check-that-your-kotlin-version-is-1-0-java-lang-illegalstateexception-unsupported-metadata-version-check-that-your-kotlin-version-is-1-0/156366)
**Author:** [@timacosta06](https://forums.kodeco.com/u/timacosta06)\ **Replies:** 0\ **Last updated:** [November 8, 2021, 4:57pm UTC](https://forums.kodeco.com/t/unsupported-metadata-version-check-that-your-kotlin-version-is-1-0-java-lang-illegalstateexception-unsupported-metadata-version-check-that-your-kotlin-version-is-1-0/156366 "2021-11-08T16:57:39Z")
08 Nov. 2021, chapter 08-multi-module-applications. After creating the onboarding module and moving things around, I was getting the following: Execution failed for task ':app:kaptDebugKotlin'. \> A failure occurred whiā€¦ --- ## [Why using a StatefulWidget to implement the first challenge solution in Chapter 5?](https://forums.kodeco.com/t/why-using-a-statefulwidget-to-implement-the-first-challenge-solution-in-chapter-5/154595)
**Author:** [@alilosoft](https://forums.kodeco.com/u/alilosoft)\ **Replies:** 13\ **Last updated:** [November 8, 2021, 3:00pm UTC](https://forums.kodeco.com/t/why-using-a-statefulwidget-to-implement-the-first-challenge-solution-in-chapter-5/154595 "2021-11-08T15:00:09Z")
Is there any reason to use a StatefullWidget to implement the solution for the first challenge in Chapter 5? I have simply used a local variable for ScrollController in the build() method of the ExploreScreen StatelessWā€¦ --- ## [Chapter 3 - textSelectionColor](https://forums.kodeco.com/t/chapter-3-textselectioncolor/156210)
**Author:** [@mitai](https://forums.kodeco.com/u/mitai)\ **Replies:** 3\ **Last updated:** [November 8, 2021, 10:21am UTC](https://forums.kodeco.com/t/chapter-3-textselectioncolor/156210 "2021-11-08T10:21:16Z")
// 4 bottomNavigationBar: BottomNavigationBar( // 5 selectedItemColor: Theme.of(context).textSelectionColor,// Deprecated // 6 items: \\[ BottomNavigationBarItem( icon: Icon(Iā€¦ --- ## [How advanced do you think augmented reality can get?](https://forums.kodeco.com/t/how-advanced-do-you-think-augmented-reality-can-get/156287)
**Author:** [@alice7890](https://forums.kodeco.com/u/alice7890)\ **Replies:** 0\ **Last updated:** [November 8, 2021, 6:13am UTC](https://forums.kodeco.com/t/how-advanced-do-you-think-augmented-reality-can-get/156287 "2021-11-08T06:13:25Z")
As we move ahead with technology, AR technology has already changed a lot of perspectives in our lives. There are many milestones that it has to reach in order to become a common technology. Now, AR technology is being ā€¦ --- ## [Ch 2 - type 'Null' is not a subtype of type 'List\' of 'function result'](https://forums.kodeco.com/t/ch-2-type-null-is-not-a-subtype-of-type-list-ingredient-of-function-result/155780)
**Author:** [@ijjtseng](https://forums.kodeco.com/u/ijjtseng)\ **Replies:** 2\ **Last updated:** [November 8, 2021, 5:54am UTC](https://forums.kodeco.com/t/ch-2-type-null-is-not-a-subtype-of-type-list-ingredient-of-function-result/155780 "2021-11-08T05:54:07Z")
In Chapter 2 towards the end, " Showing the ingredients", I copy/pasted the Expanded code but got this error message rendered in the recipe detail view: type 'Null' is not a subtype of type 'List\' of 'functiā€¦ --- ## [Rookie Question About Flutter Requirements](https://forums.kodeco.com/t/rookie-question-about-flutter-requirements/156276)
**Author:** [@droscoe](https://forums.kodeco.com/u/droscoe)\ **Replies:** 1\ **Last updated:** [November 8, 2021, 4:05am UTC](https://forums.kodeco.com/t/rookie-question-about-flutter-requirements/156276 "2021-11-08T04:05:18Z")
Iā€™m totally new to this and Iā€™m betting that I simply have a misunderstanding here. The first thing on the list of ā€œThings I Needā€ is XCode for iOS development. But I canā€™t install it on my Windows PC or build iOS appsā€¦ --- ## [Calling notifyListeners(); two successive times!](https://forums.kodeco.com/t/calling-notifylisteners-two-successive-times/156227)
**Author:** [@alilosoft](https://forums.kodeco.com/u/alilosoft)\ **Replies:** 2\ **Last updated:** [November 7, 2021, 4:24pm UTC](https://forums.kodeco.com/t/calling-notifylisteners-two-successive-times/156227 "2021-11-07T16:24:59Z")
Chapter 7 :right\_arrow: Adding the log out capability In the snippet bellow, doesnā€™t initializeApp(); notify listeners? why we should call notifyListeners(); again? void logout() { \_loggedIn = false; \_onboardā€¦ --- ## [Chapter 10: Failed to build build\_runner:build\_runner](https://forums.kodeco.com/t/chapter-10-failed-to-build-build-runner-build-runner/155988)
**Author:** [@jamieblumberg](https://forums.kodeco.com/u/jamieblumberg)\ **Replies:** 1\ **Last updated:** [November 7, 2021, 12:08am UTC](https://forums.kodeco.com/t/chapter-10-failed-to-build-build-runner-build-runner/155988 "2021-11-07T00:08:24Z")
I have run into an error that I havenā€™t been able to work around in Chapter 10: Serialization with Json. At the step where we are supposed to run flutter pub run build\_runner build in the Terminal I always get the sameā€¦ --- ## [What \*\*add Flutter to your host Android app.\*\* means?](https://forums.kodeco.com/t/what-add-flutter-to-your-host-android-app-means/156133)
**Author:** [@alilosoft](https://forums.kodeco.com/u/alilosoft)\ **Replies:** 3\ **Last updated:** [November 6, 2021, 10:41am UTC](https://forums.kodeco.com/t/what-add-flutter-to-your-host-android-app-means/156133 "2021-11-06T10:41:16Z")
In Chapter 7 at the end of section Navigator 1.0ā€™s disadvantages, there is Finally, on Android devices, the Back button might not work with Navigator 1.0 when you have nested navigators or when you add Flutter to your ā€¦ --- ## [The starter fooderlich project doesn't run](https://forums.kodeco.com/t/the-starter-fooderlich-project-doesnt-run/135713)
**Author:** [@sundraw](https://forums.kodeco.com/u/sundraw)\ **Replies:** 4\ **Last updated:** [November 5, 2021, 10:08pm UTC](https://forums.kodeco.com/t/the-starter-fooderlich-project-doesnt-run/135713 "2021-11-05T22:08:45Z")
The problem is with the Cocoapods (itā€™s a pity Apple isnā€™t rich enough to provide a package management system of their own). It always ends up with something like this: \[!\] Automatically assigning platform \`iOS\` with veā€¦ --- ## [What is the future of augmented reality?](https://forums.kodeco.com/t/what-is-the-future-of-augmented-reality/156017)
**Author:** [@alice7890](https://forums.kodeco.com/u/alice7890)\ **Replies:** 0\ **Last updated:** [November 5, 2021, 5:26am UTC](https://forums.kodeco.com/t/what-is-the-future-of-augmented-reality/156017 "2021-11-05T05:26:19Z")
Augmented reality is the future of advertisement and marketing strategies. This is now becoming a new technology that people want to experience every day. They are excited about the immersive technology. People like inteā€¦ [Previous page](https://forums.kodeco.com/c/books/6.md?page=36) [Next page](https://forums.kodeco.com/c/books/6.md?page=38)