kotlinlang #multiplatform

Hi, I’m using Kotlin multiplatform in one of my iOS projects. I need to write several features which will run in the background while the app is not running (main thread is not allowed in background tasks, the OS will silently kill the task if it tries to use main thread), these include things like background tasks, widgets, etc. I’ve been running into problems with kotlin multiplatform code crashing due to the current memory model and I’ve been investigating. Has anyone been able to successfully use kotlin multiplatform for background tasks on iOS?

Hadji Musaev

09/20/2021, 11:16 AM

Hi guys! I wanted to discuss this topic: https://youtrack.jetbrains.com/issue/KT-30878 I wanted to write a small library that would contain some business logic which should be shared across a service, an Android app and an iOS app. I can compile it separately for Java and Android, but I’m struggling to find the best way to structure the project in such a way that would allow me to build 3 different artifacts from the same code base. Has anyone had to solve a similar problem?

Forrest Pangborn

09/20/2021, 7:46 PM

has anyone had trouble including

kotlinx-atomicfu

as a

common

dependency? i tried for awhile to include

0.16.3

as such for awhile today with the artifact specified in the project

README

. it claims the gradle plugin approach can be avoided if intended use is just within a

common

sourceset, but i couldn't get it to work unless i used a different artifact name. didn't work:

org.jetbrains.kotlinx:atomicfu-common

worked:

org.jetbrains.kotlinx:atomicfu

brabo-hi

09/20/2021, 8:47 PM

Hi, is there a kmm library for storing settings for both android/ios ?

brabo-hi

09/20/2021, 9:13 PM

how should we handle BigDecimal and monetary values in KMM ?

Amritansh

09/20/2021, 10:23 PM

Hi, I am getting this when I try to build

./gradlew :shared:build

my KMM project

Task :shared:compileKotlinMetadata FAILED

and in the stacktrace I am getting this

Unresolved reference: newSingleThreadContext

. I am using kotlin : 1.5.31 and coroutines version

1.5.2-native-mt

. Any idea what might be the issue? I had to comment out

#kotlin.mpp.enableGranularSourceSetsMetadata=true
#kotlin.native.enableDependencyPropagation=false

in the gradle.properties since sql delight does not support hmpp. can that be the issue here?

jean

09/21/2021, 9:06 AM

I’m trying to tesmsqldelight code the same way it is done there : https://github.com/touchlab/KaMPKit/blob/main/shared/src/commonTest/kotlin/co/touchlab/kampkit/SqlDelightTest.kt but I get the following error. Any idea what I’m doing wrong?

kotlin.IllegalStateException: There is no event loop. Use runBlocking { ... } to start one.

Sebastian Oßner

09/21/2021, 9:53 AM

Hi there people, I am looking into the use of KMM for our company, but I am unsure what amount of work that would entail. We currently use J2Objc to convert our (quite large) stack to ObjC and build a Framework out of that. Our Android application is quite small, mainly using existing Java libraries that at some point interface with C++ libraries via JNI. The main point of the application is to connect to devices on the network and transmit vast amounts of data (but everything is already handled in the underlying libraries) Basically the question is if simply switching from J2ObjC to KMM seems feasible (without too much overhead)

Borja

09/21/2021, 1:39 PM

Hi there. I’m trying to use an objc library through cinterop but it crashes on run time with message

dyld: Library not loaded:

Does anyone had the same issue? I built a minimum repro repo here: https://github.com/flaquir4/MinimumRepro

sushma nayak

09/21/2021, 4:43 PM

I use kotlinxserialization 1.2.2 and use

ignoreUnknownKeys = true

. Still get the error ERROR -
Use 'ignoreUnknownKeys = true' in 'Json {}' builder to ignore unknown keys.
My json config -

Json {
    isLenient = true
    ignoreUnknownKeys = true
    prettyPrint = true
  }

Scott Kruse

09/21/2021, 7:50 PM

Any know of any projects / articles w/ kmp with native target + flutter front end?

mkrussel

09/21/2021, 8:40 PM

After installing Xcode 13, I can no longer create the interop libraries for my framework generated from the Xcode. I've got building the framework as a dependency of the interop task in gradle. This worked before when I was using an Xcode 12.x release. It's an Objective-C framework. The error message is just that it could not build the module.

/var/folders/qt/q46m5kx100j30g9hdl4rzf_h0000gn/T/16722905496877169974.m:1:9: fatal error: could not build module 'PangeaMapView'

Does Kotlin not support outputs from Xcode 13? Are there any logs with more detailed information about the failure? I'm on Kotlin 1.5.21 to work with Jetpack Compose.

👀 1

MarkRS

09/22/2021, 8:44 AM

Anyone else seeing https://github.com/kotlin-hands-on/kmm-networking-and-data-storage/issues/9 "again"? Seems to have happened here after the latest kotlin plugin update. None of the fixes I can find seems to fix it.

Nicolas Verinaud

09/22/2021, 10:59 AM

[RESOLVED ✅] Hi ! I am writing a shared interface with a suspend function. In iOS it generates a protocol with a method with a completionHandler which is great. Problem is how can I handle cancellation ? My shared interface :

interface CanRetrieveAuthorizationToken {
    suspend fun getToken(): String
}

The corresponding protocol :

public protocol CanRetrieveAuthorizationToken {
   
    /**
     @note This method converts instances of CancellationException to errors.
     Other uncaught Kotlin exceptions are fatal.
    */
    func getToken(completionHandler: @escaping (String?, Error?) -> Void)
}

✅ 1

Justin

09/22/2021, 5:44 PM

[KMP Pattern Question] I am building a design system library that will be consumed by Android, iOS, macOS, and Web. The library will vend everything from primitives (e.g. colors/gradients/fonts/etc.) to controls (e.g. buttons/selectors/text fields/etc.). Simple enough. Here's where things got thorny: This app also needs to specialize the appearance of everything based on a

theme

, which is a global appearance setting (you can think of it sort of like light/dark mode) that is only known at runtime. In other words, this library needs to return everything from

Color.primary

FloatingActionButton()

(for example) based on the runtime-determined

theme

of the app. The theme doesn't change across the app lifecycle (i.e. we know right at init what the theme will be and it's a constant for the rest of that app instance's existence), which is helpful. What I'm struggling with is where this

theme

setting should live. All of the components in this design system library will need to be able to read this value to work correctly, so I can imagine having it be a global var that consumers can set on the library itself. But when I attempt to build something like this:

interface Theme {
    companion object {
        var value: Theme = DefaultTheme()
    }
}

class DefaultTheme(...): DefaultTheme {...}

...I see the following warning in the console:

w: Theme.kt: With old Native GC, variable in singleton without @ThreadLocal can't be changed after initialization

And I'd generally like to avoid stored mutable state with my K/N libraries if at all possible. Would love to hear peoples' thoughts on the most idiomatic/safest approach to this!

Jim

09/22/2021, 8:44 PM

👋 is there something akin to

@JsName

and

@JVMName

for native? Accessing the resulting classes from c++ is pretty unpleasant

<http://kotlin.com|kotlin.com>.jim.blah.Blah

. If there isn’t I’m considering putting a shim in my native source set at the top right under kotlin so at least it would be

kotlin.Blah

. Am I missing something here? Thanks!

➕ 1

hallvard

09/22/2021, 8:57 PM

One of my JvmTests complains that some parameters to a constructor are missing. This is for an expect/actual class with 9 parameters in the constructor, but only the first three are needed, since the last 6 default to null. But the null values are set in the

expect

declaration, since

actual

functions cannot have default argument values. I have the

@JvmOverloads

annotation in the actual implementation (Idea warns me it has no effect since there are no default arguments), and also tried to include it in the expect implementation (no warning from Idea), but to no avail. So my test doesn't compile and cannot run ... What did I miss?

Gene Cahill

09/23/2021, 5:34 PM

How do I set up release / debug variants for android in a multiplatform project?

saket

09/24/2021, 4:18 AM

After updating to AGP, Xcode is failing to build my project because gradle is unable to read

JAVA_HOME

variable. It seems like Xcode doesn’t source any shell profile during its build process causing

JAVA_HOME

to resolve to

null

. I checked this by adding this to my `build.gradle`:

println("JAVA_HOME = ${System.getenv("JAVA_HOME")}")

Folks who’re using AGP 7.0, have any of you run into this before?

Michal Klimczak

09/24/2021, 8:16 AM

I have a small but annoying issue. I have a monorepo for android and ios app and a shared module that is built into xcframework with

gradle :shared:assembleSharedDebugXCFramework

. This gradle comand is run as a Build Phase in xcode and the framework is embedded via framework search paths. Reproducing issue: 1. Change sth in shared module code. 2. Run build in xcode (takes a lot of time because xcframework is fully rebuilt). 3. The change is applied, everything fine. ✅ 4. Run build in xcode without changing anything (quick, the xcframework is not rebuilt fully). This step is crucial, without it the changes are applied just fine. 5. Change sth in shared module code again. 6. Run build in xcode (takes a lot of time because xcframework is fully rebuilt). 7. The change is not applied ‼️ 8. Run build in xcode without changing anything (quick, the xcframework is not rebuilt fully). 9. Only now the change is applied. ✅ I would rather say it's an xcode issue, but not sure. It's like in pt.7 the xcode built the framework but somehow didn't pick it yet. Only the next time. I think I had sth similar with regular frameworks and

packForXcode

but not 100% sure.

FadiBouteraa

09/24/2021, 12:48 PM

Hi #kmm help me plz Undefined symbols for architecture arm64: "_OBJC_CLASS_$_SharedLoginPayload", referenced from: objc-class-ref in LoginViewModel.o

ivano

09/24/2021, 7:06 PM

There was a library to convert swift ui to compose but is not updated anymore. How is that possible if we could convert swift ui then kotlin would eat flutter for breakfast

Robert

09/25/2021, 7:36 AM

Any clue how to fix this in intellij 2021.2?

This version of the Android Support plugin for IntelliJ IDEA (or Android Studio) cannot open this project, please retry with version 2020.3.1 or newer.

avinash sai pavan munnangi

09/26/2021, 9:33 AM

Hi all, Im new to KMM and Im trying to hit the api and get the data using coroutines. it is working fine in android facing issues in ios . can anyone help me

Rohan Maity

09/26/2021, 11:20 AM

Hello, I am working on Multiplatform project targeting

android, iOS and Web

For the web app somehow my generated JS file is getting blocked

The resource was blocked due to MIME type ("text/html") mismatch (X-Content-Type-Options: nosniff).

I have just done the simple

Hello world

only, Its working on android and iOS has anyone encountered the same issue ? Any help here would be appreciated More info in replies

robjperez

09/27/2021, 11:10 AM

Hey there!, I’m having some trouble when using a cocoapods dep in the ios build, It was working well and now I’m suspecting that xcode new version has messed up something. I’m getting

Exception in thread "main" java.lang.Error: /var/folders/0d/4r7ddycs7msfghjht2w29hdw0000gq/T/12354154991012977801.m:1:9: fatal error: could not build module 'Foo'
        at org.jetbrains.kotlin.native.interop.indexer.UtilsKt.ensureNoCompileErrors(Utils.kt:192)
        at org.jetbrains.kotlin.native.interop.indexer.ModuleSupportKt.getModulesASTFiles(ModuleSupport.kt:68)
        at org.jetbrains.kotlin.native.interop.indexer.ModuleSupportKt.getModulesInfo(ModuleSupport.kt:14)
        at org.jetbrains.kotlin.native.interop.gen.jvm.MainKt.buildNativeLibrary(main.kt:531)
        at org.jetbrains.kotlin.native.interop.gen.jvm.MainKt.processCLib(main.kt:268)
        at org.jetbrains.kotlin.native.interop.gen.jvm.MainKt.interop(main.kt:76)
        at org.jetbrains.kotlin.cli.utilities.InteropCompilerKt.invokeInterop(InteropCompiler.kt:45)
        at org.jetbrains.kotlin.cli.utilities.MainKt.mainImpl(main.kt:38)
        at org.jetbrains.kotlin.cli.utilities.MainKt.main(main.kt:60)

in the interop task

:sdk:cinteropFooIosArm64

It is very hard to get any clue with that error 😞

Tarika Chawla

09/27/2021, 2:43 PM

Hi all, Anyone has any experience integrating a KMM in a Development Pod in iOS instead of the project itself? I was able to import the KMM in the development pod by adding it through podspec file but hitting a roadblock when I call those functions.

jimmyt

09/27/2021, 4:53 PM

I'm working on a KMM project targeting iOS and Android, and occasionally when I try to edit the KMM module's build.gradle.kts file, the entire thing lights up with "Unresolved reference" errors. At the time of my last commit, the project had no errors. Now, even though build.gradle.kts is completely unchanged from my last commit, it has 48 "Unresolved reference" errors, most of which are on basic keywords like "implementation" and "sourceSets". Any idea what could be causing this?

MarkRS

09/28/2021, 10:14 AM

Suddenly all over my code I'm getting red lines complaining "The feature 'multi platform project' is experimental and should be enabled explicitly", even directly underneath the annotation @ExperimentalMultiplatform. I've now added the compiler option -Xmulti-platform (via gradle, I use AS), but I still get the red lines. Despite this the app builds and runs, although it crashes immediately, perhaps with a related error but I'm still tracking that down.

Title

MarkRS

09/28/2021, 10:14 AM

louiscad

09/28/2021, 1:05 PM

Can you pinpoint the last commit where you didn't have the issue and inspect what changed since then?

MarkRS

09/28/2021, 1:30 PM

Good thought. Yes I can and yes I will 🙂

Etienne

10/27/2021, 10:15 PM

@MarkRS I have the same issue in my (brand new) project, did you find a fix?

MarkRS

10/28/2021, 10:14 AM

I don't have this issue any more @Etienne, but I'm sorry to say I don't know what I did that fixed it 😞 . Does your code run? I suspect it was something in build files (or is that too obvious to even say?). I do still have red lines everywhere, import statements complaining about not finding io.ktor and similar, but again the code builds and runs. @ephemient pointed out that "plugins don't work in KMM", which seems too much of a blanket statement, but it does seem to me that they perhaps "don't work" to the extent of preventing ktlint seeing some thing.

Etienne

10/28/2021, 12:26 PM

Yah my code ran/runs, after mucking about for a whole day, I found that the latest Bumblebee AS 'fixes' the issue. I tried everything I could find/think of on the Chipmunk AS release, no dice.

I'll try to find a place to report the issue that makes sense. Doesn't seem like Jetbrains thinks its on their end, from the issues I found being closed and all. Maybe it's one of those "AS uses older components and it'll eventually be fixed" type deals.

ephemient

10/28/2021, 7:42 PM

https://youtrack.jetbrains.com/issue/KT-27683 more like "plugins that aren't built for MPP, don't work with MPP" than "plugins don't work"

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