# 📚 Official Books **URL:** https://forums.kodeco.com/c/books/6.md?page=11 [Latest](https://forums.kodeco.com/latest.md) · [Categories](https://forums.kodeco.com/categories.md) · [Tags](https://forums.kodeco.com/tags.md) **Page:** 12 --- ## [Chapter 7: Routes & Navigation](https://forums.kodeco.com/t/chapter-7-routes-navigation/189816)
**Author:** [@ifystella](https://forums.kodeco.com/u/ifystella)\ **Replies:** 0\ **Last updated:** [July 26, 2023, 8:55am UTC](https://forums.kodeco.com/t/chapter-7-routes-navigation/189816 "2023-07-26T08:55:20Z")
I am getting this error, whenever i try to navigate to the onboarding screen. What could be the issue, especially when i add the redirect handler code. --- ## [Relation not loaded: Parent\(key: userID)](https://forums.kodeco.com/t/relation-not-loaded-parent-acronym-user-key-userid/133417)
**Author:** [@tsidenfaden](https://forums.kodeco.com/u/tsidenfaden)\ **Replies:** 5\ **Last updated:** [July 26, 2023, 5:06am UTC](https://forums.kodeco.com/t/relation-not-loaded-parent-acronym-user-key-userid/133417 "2023-07-26T05:06:00Z")
Hello, I’m getting this error when trying to do the /api/acronyms//user call in Chapter 9. I’ve checked my code against the final code in the tutorial materials and it looks the same. I’m able to post a new acronym with… --- ## [Chapter 8: Deep Links. Failing opening the IOS simulator](https://forums.kodeco.com/t/chapter-8-deep-links-failing-opening-the-ios-simulator/185022)
**Author:** [@magenti](https://forums.kodeco.com/u/magenti)\ **Replies:** 1\ **Last updated:** [July 24, 2023, 3:47pm UTC](https://forums.kodeco.com/t/chapter-8-deep-links-failing-opening-the-ios-simulator/185022 "2023-07-24T15:47:11Z")
Hi, The xcrun simctl openurl booted 'fooderlich://raywenderlich.com/1' command over the fresh, unmodified starter project of Chapter 8 (deep links), throws the following error in my Mac: An error was encountered pr… --- ## [Preferences null check](https://forums.kodeco.com/t/preferences-null-check/189727)
**Author:** [@levent31](https://forums.kodeco.com/u/levent31)\ **Replies:** 0\ **Last updated:** [July 23, 2023, 6:29pm UTC](https://forums.kodeco.com/t/preferences-null-check/189727 "2023-07-23T18:29:33Z")
According to the requirement, is it necessary to use getString(KEY\_TOKEN, "").orEmpty() instead of getString(KEY\_TOKEN, "") ? The getString function already defaults to an empty string ("" ) and automatically returns an … --- ## [Update plans to update?](https://forums.kodeco.com/t/update-plans-to-update/189706)
**Author:** [@rphuber](https://forums.kodeco.com/u/rphuber)\ **Replies:** 0\ **Last updated:** [July 22, 2023, 5:43pm UTC](https://forums.kodeco.com/t/update-plans-to-update/189706 "2023-07-22T17:43:28Z")
Any plans to update this book? I know some of the tutorials still use cocoa pods and it hasn’t been updated in a few years. --- ## [Successfully hiding the Editor Pane for Notepad - Ch1](https://forums.kodeco.com/t/successfully-hiding-the-editor-pane-for-notepad-ch1/189702)
**Author:** [@cupofjoe](https://forums.kodeco.com/u/cupofjoe)\ **Replies:** 0\ **Last updated:** [July 22, 2023, 1:23pm UTC](https://forums.kodeco.com/t/successfully-hiding-the-editor-pane-for-notepad-ch1/189702 "2023-07-22T13:23:37Z")
I wasn’t able to get this to work as detailed in the book using a MacOS VM. Cutting and pasting verbatim from the book I would get this error: po \[$rdi setHidden:!(BOOL)\[$rdi isHidden\]\]; error: expression failed to pa… --- ## [Why is the Texture not being applied to Quad?](https://forums.kodeco.com/t/why-is-the-texture-not-being-applied-to-quad/189691)
**Author:** [@trhenrylewis](https://forums.kodeco.com/u/trhenrylewis)\ **Replies:** 2\ **Last updated:** [July 22, 2023, 10:55am UTC](https://forums.kodeco.com/t/why-is-the-texture-not-being-applied-to-quad/189691 "2023-07-22T10:55:03Z")
So in trying to stretch myself and figure things out I went ahead and tried to do something I thought would be relatively simple based on what I have been learning in Metal by Tutorials but of course got stumped. What I… --- ## [Errata for Combine: Asynchronous Programming With Swift 4th Edition](https://forums.kodeco.com/t/errata-for-combine-asynchronous-programming-with-swift-4th-edition/189578)
**Author:** [@jellodiil](https://forums.kodeco.com/u/jellodiil)\ **Replies:** 0\ **Last updated:** [July 19, 2023, 12:09am UTC](https://forums.kodeco.com/t/errata-for-combine-asynchronous-programming-with-swift-4th-edition/189578 "2023-07-19T00:09:41Z")
Creating this topic to catch any typos and bugs in the 4th Edition of Combine: Asynchronous Programming With Swift. --- ## [Chapter 16: handling 2D and 3D inputs](https://forums.kodeco.com/t/chapter-16-handling-2d-and-3d-inputs/189022)
**Author:** [@tchelyzt](https://forums.kodeco.com/u/tchelyzt)\ **Replies:** 6\ **Last updated:** [July 17, 2023, 10:39pm UTC](https://forums.kodeco.com/t/chapter-16-handling-2d-and-3d-inputs/189022 "2023-07-17T22:39:38Z")
Hello Caroline ( as it’s likely you who will answer me :smile: ) I’m working on Chapter 16, trying to understand it better. Indeed, I’ve successfully loaded an array of Floats, carried out a calculation on them and comp… --- ## [Fails to Gradle sync](https://forums.kodeco.com/t/fails-to-gradle-sync/188988)
**Author:** [@lenduya](https://forums.kodeco.com/u/lenduya)\ **Replies:** 1\ **Last updated:** [July 17, 2023, 3:50pm UTC](https://forums.kodeco.com/t/fails-to-gradle-sync/188988 "2023-07-17T15:50:44Z")
I’m at the start of chapter 02 and already am encountering Gradle issues due to how out of date the book is. When I create the directory BuildSrc and its corresponding file build.gradle.kts, first it requires me to upda… --- ## [Errata for Kotlin Multiplatform by Tutorials 1st Edition](https://forums.kodeco.com/t/errata-for-kotlin-multiplatform-by-tutorials-1st-edition/166855)
**Author:** [@jellodiil](https://forums.kodeco.com/u/jellodiil)\ **Replies:** 18\ **Last updated:** [July 17, 2023, 3:07pm UTC](https://forums.kodeco.com/t/errata-for-kotlin-multiplatform-by-tutorials-1st-edition/166855 "2023-07-17T15:07:53Z")
Creating this topic to catch any typos and bugs in the 1st Edition of Kotlin Multiplatform by Tutorials. --- ## [Chapter 5: Expression - \`error: cannot find '$R1' in scope\`](https://forums.kodeco.com/t/chapter-5-expression-error-cannot-find-r1-in-scope/189395)
**Author:** [@tonygo](https://forums.kodeco.com/u/tonygo)\ **Replies:** 1\ **Last updated:** [July 14, 2023, 8:22am UTC](https://forums.kodeco.com/t/chapter-5-expression-error-cannot-find-r1-in-scope/189395 "2023-07-14T08:22:49Z")
I’m trying to use the allocated variables given after p self ($R1 for instance), but after resuming the process and then pausing it again, I cannot access to $R1. (lldb) p self (Signals.MainContainerViewController) $R1 … --- ## [Flutter Apprentice 4th edition: ETA](https://forums.kodeco.com/t/flutter-apprentice-4th-edition-eta/189211)
**Author:** [@sampathl](https://forums.kodeco.com/u/sampathl)\ **Replies:** 4\ **Last updated:** [July 11, 2023, 7:04pm UTC](https://forums.kodeco.com/t/flutter-apprentice-4th-edition-eta/189211 "2023-07-11T19:04:43Z")
Hi, Any ETA for Flutter Apprentice 4th edition? Thanks! --- ## [Metal-cpp and SwiftUI](https://forums.kodeco.com/t/metal-cpp-and-swiftui/188228)
**Author:** [@nghiaphamsg](https://forums.kodeco.com/u/nghiaphamsg)\ **Replies:** 3\ **Last updated:** [July 10, 2023, 12:27pm UTC](https://forums.kodeco.com/t/metal-cpp-and-swiftui/188228 "2023-07-10T12:27:15Z")
Hello everyone I want to take advantage of my knowledge of C++ more. Is there a way to combine SwiftUI and metal-cpp ? (only examples using UIKit) I like using SwiftUI over than UIKit Thank you! --- ## [Are parallel views possible](https://forums.kodeco.com/t/are-parallel-views-possible/186223)
**Author:** [@tchelyzt](https://forums.kodeco.com/u/tchelyzt)\ **Replies:** 6\ **Last updated:** [July 9, 2023, 9:20pm UTC](https://forums.kodeco.com/t/are-parallel-views-possible/186223 "2023-07-09T21:20:07Z")
I’m far from finished the book but scanning ahead it doesn’t seem to address my following question: If I have a mesh and want to view it from several perspectives simultaneously (in separate views), it would seem that I… --- ## [Trying to figure out view transitions](https://forums.kodeco.com/t/trying-to-figure-out-view-transitions/189132)
**Author:** [@sundraw](https://forums.kodeco.com/u/sundraw)\ **Replies:** 0\ **Last updated:** [July 8, 2023, 7:01am UTC](https://forums.kodeco.com/t/trying-to-figure-out-view-transitions/189132 "2023-07-08T07:01:18Z")
I’m in Chapter 20 and trying to follow the logic using a very simple example. Here’s the code: struct ContentView: View { @State var change = false var body: some View { Rectangle() .fo… --- ## [Chapter 9: Possible errata in Converting Indexes Between Encoding Views section](https://forums.kodeco.com/t/chapter-9-possible-errata-in-converting-indexes-between-encoding-views-section/189044)
**Author:** [@rodaguilera](https://forums.kodeco.com/u/rodaguilera)\ **Replies:** 0\ **Last updated:** [July 5, 2023, 11:41pm UTC](https://forums.kodeco.com/t/chapter-9-possible-errata-in-converting-indexes-between-encoding-views-section/189044 "2023-07-05T23:41:01Z")
The Xcode compiler advised unwrapping the optional (\[arrowIndex!\]) in the code below Converting Indexes Between Encoding Views As you saw earlier, you use indexes to access grapheme clusters in a string. For example, u… --- ## [Time Complexity for finding edges in Adjacency Matrix in Graph](https://forums.kodeco.com/t/time-complexity-for-finding-edges-in-adjacency-matrix-in-graph/188722)
**Author:** [@nicks101](https://forums.kodeco.com/u/nicks101)\ **Replies:** 1\ **Last updated:** [July 4, 2023, 11:30pm UTC](https://forums.kodeco.com/t/time-complexity-for-finding-edges-in-adjacency-matrix-in-graph/188722 "2023-07-04T23:30:10Z")
In Chapter 20, Graphs, the Graph Analysis for Adjacency List and Matrix is provided. The Time Complexity for Finding Edges in Adjacency Matrix is specified as O(1). Although in the function edges(Vertex\ source), we … --- ## [What is the principle of asynchronous submitted tasks to a serial queue?](https://forums.kodeco.com/t/what-is-the-principle-of-asynchronous-submitted-tasks-to-a-serial-queue/183915)
**Author:** [@iaccount](https://forums.kodeco.com/u/iaccount)\ **Replies:** 2\ **Last updated:** [July 4, 2023, 12:04am UTC](https://forums.kodeco.com/t/what-is-the-principle-of-asynchronous-submitted-tasks-to-a-serial-queue/183915 "2023-07-04T00:04:27Z")
How can a serial queue that has submitted tasks asynchronously keep doing some other work (for example, UI related work) on the current thread while those tasks are not yet completed? As we know, a serial queue can run o… --- ## [Chapter 12: Basic Animation Principles](https://forums.kodeco.com/t/chapter-12-basic-animation-principles/186496)
**Author:** [@matviienko](https://forums.kodeco.com/u/matviienko)\ **Replies:** 11\ **Last updated:** [June 30, 2023, 3:05pm UTC](https://forums.kodeco.com/t/chapter-12-basic-animation-principles/186496 "2023-06-30T15:05:29Z")
Hey all, I get the following error when starting the scene from a starter project for Chapter 12: /Assets/Scenes/Kitchen/LightingData.asset’. File may be corrupted or was serialized with a newer version of Unity. My Un… --- ## [What is Chunk count in Modern Concurrency Unit 3?](https://forums.kodeco.com/t/what-is-chunk-count-in-modern-concurrency-unit-3/188853)
**Author:** [@anthony\_tran](https://forums.kodeco.com/u/anthony_tran)\ **Replies:** 0\ **Last updated:** [June 30, 2023, 8:31am UTC](https://forums.kodeco.com/t/what-is-chunk-count-in-modern-concurrency-unit-3/188853 "2023-06-30T08:31:10Z")
Hello, iOS champions! In the struct ByteAccumulator, What is chunk count? is that a block unit of bytes? why its value is the size of the file divided by 20? why 20? struct ByteAccumulator: CustomStringConvertible { … --- ## [What do these two key points mean at the end of Chapter 17, Protocols?](https://forums.kodeco.com/t/what-do-these-two-key-points-mean-at-the-end-of-chapter-17-protocols/188670)
**Author:** [@1097278366](https://forums.kodeco.com/u/1097278366)\ **Replies:** 7\ **Last updated:** [June 28, 2023, 5:10am UTC](https://forums.kodeco.com/t/what-do-these-two-key-points-mean-at-the-end-of-chapter-17-protocols/188670 "2023-06-28T05:10:49Z")
If you create an extension on a protocol that isn’t declared in the protocol, conforming types cannot override the extension. If you create an implementation in an extension declared in the protocol, conforming types ca… --- ## [androidx.constraintlayout.widget.ConstraintLayout cannot be cast to android.widget.LinearLayout](https://forums.kodeco.com/t/androidx-constraintlayout-widget-constraintlayout-cannot-be-cast-to-android-widget-linearlayout/188713)
**Author:** [@takix](https://forums.kodeco.com/u/takix)\ **Replies:** 0\ **Last updated:** [June 27, 2023, 12:22pm UTC](https://forums.kodeco.com/t/androidx-constraintlayout-widget-constraintlayout-cannot-be-cast-to-android-widget-linearlayout/188713 "2023-06-27T12:22:08Z")
I am getting such an error while compiling the application. When I make a LinearLayout, the error disappears, but when I use a ConstraitLayout, the error appears. Java Class LinearLayout linearLayout = findV… --- ## [Chapter 1 - Why both functions called in Ternary expression?](https://forums.kodeco.com/t/chapter-1-why-both-functions-called-in-ternary-expression/188661)
**Author:** [@tegieng](https://forums.kodeco.com/u/tegieng)\ **Replies:** 2\ **Last updated:** [June 27, 2023, 8:17am UTC](https://forums.kodeco.com/t/chapter-1-why-both-functions-called-in-ternary-expression/188661 "2023-06-27T08:17:31Z")
Can anyone explain why both functions get called in Ternary expression here: func ifelse(\_ condition: Bool, \_ valueTrue: Any, \_ valueFalse: Any) -\> Any { condition ? valueTrue : valueFalse } func expensiveValue1() -\>… --- ## [Chapter 3, Mutating while Iterating error?](https://forums.kodeco.com/t/chapter-3-mutating-while-iterating-error/183863)
**Author:** [@kamiwa](https://forums.kodeco.com/u/kamiwa)\ **Replies:** 2\ **Last updated:** [June 25, 2023, 11:36pm UTC](https://forums.kodeco.com/t/chapter-3-mutating-while-iterating-error/183863 "2023-06-25T23:36:56Z")
override fun remove() { // 1 if (index == 1) { list.pop() } else { // 2 val prevNode = list.nodeAt(index - 2) ?: return // 3 list.removeAfter(prevNode) lastNode = prevNode } index-- } I… --- ## [About Challenge 2 solution code in Chapter 6 Mixins](https://forums.kodeco.com/t/about-challenge-2-solution-code-in-chapter-6-mixins/183836)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 2\ **Last updated:** [June 23, 2023, 1:25pm UTC](https://forums.kodeco.com/t/about-challenge-2-solution-code-in-chapter-6-mixins/183836 "2023-06-23T13:25:57Z")
The solution code try to implements Comparable\ My code don’t have the \ type declaration, see below: class Platypus extends Animal with EggLayer implements Comparable { @override void eat() { … --- ## [\[Chapter 23\] challenge project](https://forums.kodeco.com/t/chapter-23-challenge-project/183470)
**Author:** [@quaternionboy](https://forums.kodeco.com/u/quaternionboy)\ **Replies:** 3\ **Last updated:** [June 26, 2023, 10:42am UTC](https://forums.kodeco.com/t/chapter-23-challenge-project/183470 "2023-06-26T10:42:46Z")
It would be awesome the project… Maybe with some animated usdz sketchfab free stuff ?!? --- ## [Xcode Push Notification](https://forums.kodeco.com/t/xcode-push-notification/183423)
**Author:** [@ultrapyromane](https://forums.kodeco.com/u/ultrapyromane)\ **Replies:** 5\ **Last updated:** [June 25, 2023, 11:46pm UTC](https://forums.kodeco.com/t/xcode-push-notification/183423 "2023-06-25T23:46:11Z")
Hello, I followed this tutorial: Unfortunately, I have not generated any tokens, what am I doing wrong? --- ## [About fold function in Chapter 2 anonymous function](https://forums.kodeco.com/t/about-fold-function-in-chapter-2-anonymous-function/183226)
**Author:** [@ellery](https://forums.kodeco.com/u/ellery)\ **Replies:** 3\ **Last updated:** [June 26, 2023, 2:17am UTC](https://forums.kodeco.com/t/about-fold-function-in-chapter-2-anonymous-function/183226 "2023-06-26T02:17:08Z")
const evens = \[2, 4, 6, 8, 10, 12\]; final total = evens.fold\( 0, (sum, element) =\> sum + element, ); Hi I don’t quite understand why I need to add \ after fold? What is the implication of it? However, I co… --- ## [Tests failing for \`Writing tests for Platform\` section](https://forums.kodeco.com/t/tests-failing-for-writing-tests-for-platform-section/183221)
**Author:** [@talhamir](https://forums.kodeco.com/u/talhamir)\ **Replies:** 2\ **Last updated:** [June 25, 2023, 11:40pm UTC](https://forums.kodeco.com/t/tests-failing-for-writing-tests-for-platform-section/183221 "2023-06-25T23:40:44Z")
The tests from chapter 8, section Writing tests for Platform, are failing for me. When I run all the tests using the command ./gradlew :shared:allTests, it gives me this error: \> Task :shared:iosSimulatorArm64Test Inval… [Previous page](https://forums.kodeco.com/c/books/6.md?page=10) [Next page](https://forums.kodeco.com/c/books/6.md?page=12)