kotlinlang #multiplatform

Hello, I am new to Kotlin Multiplatform. I want to make a mobile app in ios and android. I am trying to implement a third party library written in C/C++. I want to create the following function in androidMain :

fun setContext(currentActivity: Activity){
	connector.setUIContext(currentActivity) // this function is from the third party library
}

I wonder how I could access the type Activity. It looks it does not recognise it or the android api is not accessible. Do I need to add anything in the build.gradle.kts? Thanks for your help

dimsuz

04/21/2020, 12:54 PM

I see that this is the question which was asked before, but what is the current best solution on sharing string resources + localization between platforms? Is there any? Does everyone use

moko-resources

? Or doesn't bother and duplicates?

kkovach

04/21/2020, 1:03 PM

I'm getting the following error when trying to compile my shared multiplatform code. I'm guessing it's some sort of version mismatch with something, but I cannot figure it out. Any help would be appreciated.

curioustechizen

04/21/2020, 3:38 PM

In a multiplatform module that has

commonMain

and

iosMain

, I want to create a

iosTest

folder that uses iOS-specific code for writing tests to be run on the simulator. I've looked around but I think all the info I find is out-dated. What's the latest on this?

Jess Brent

04/21/2020, 7:08 PM

is there a way to prepend the

com.whatever.whatever

for import statements one platform, but not another? i can’t really come up with the exact phrase to google here so i’m a little SoL

saket

04/22/2020, 4:59 AM

Along the same lines: now that I’m starting to develop for macOS, I’ve noticed that none neither the official guides nor the other blogs talk about the feedback loop for native development with KMP. When changes to the common module is made, they can be used immediately from JVM or Android modules. That does not seem to be the case for native platforms. I have to rebuild my macOS project from xcode everytime to see new changes. Is that expected?

curioustechizen

04/22/2020, 7:57 AM

Is there a reference documentation for understanding the implicit dependencies between source sets in KMP? For example,

androidMain

and

iosMain

implicitly depend on

commonMain

. How about tests? Do

androidTest

and

iosTest

implicitly depend on

commonTest

? This seems intuitive, but is it documented somewhere?

gabin

04/22/2020, 2:48 PM

Hi guys, does this commit mean that google wants to expand its View hierarchy on desktop with Kotlin MPP? https://android-review.googlesource.com/c/platform/frameworks/support/+/1290729

Jan Stoltman

04/22/2020, 3:40 PM

Hey guys, are there any tips and tricks on how to improve kotlin/native compilation speed? Right now my project takes around 20min to build .framework for ios and just around 3min for android. Is it a common issue for multiplatform projects or is something wrong with my setup?

dimsuz

04/22/2020, 4:49 PM

How can I set

kotlinOptions.jvmTarget = "1.8"

for android target? Without it I have an error:

Cannot inline bytecode built with JVM target 1.8 into bytecode that is being built with JVM target 1.6

I tried

android("android") {
        compilations.main.kotlinOptions {
            jvmTarget = "1.8"
        }
    }

And it doesn't work, gives a DSL error.

Matt Toal

04/22/2020, 10:29 PM

Any recommendations on how to set up multiple multiplatform projects together? I have something like projects A and B with a shared core project. My javascript output for project A has the shared code packaged with it, but my android aar for project A does not. I can publish the aar for the shared project, and have the consuming android project pull in both as a dependency, but it seems a little weird that javascript output is combined while the android isn't.

Rak

04/23/2020, 3:10 PM

Hi, I’ve been meaning to start playing with mpp for android/ios. Yesterday, i listened to a podcast (Talking Kotlin) and they seem to imply that there are still a lot of issues running the shared code on iOS. Does anyone have more data on this? Is it bad that its not production ready? Or are their work arounds I need to investigate?

Sam Garfinkel

04/23/2020, 4:37 PM

What’s the best approach to making an existing JVM library (dependency-free) multiplatform compatible? I see two options, reimplement all Java in Kotlin as a common module, or implement just the API with

expect

in the common and delegate to the Java library on the JVM, and other similar libraries on their respective platforms (like a swift library with the same capability on Mac/iOS, etc.). Is one better than the other?

j.l.

04/23/2020, 7:28 PM

I was playing around with KMP building, testing some Android/iOS features. This was about a week or two ago. I noticed that whenever I am working in IntelliJ and make updates to the shared code in IntelliJ such as adding a function to a shared class, then switch over to Xcode to try and use this function, it takes a really long time for the function to show up in Xcode's autocomplete. The function is not recognized either and causes compilation errors. Sometimes it takes so long that I have to invalidate caches and restart in order for the function to show up in Xcode. Just thought I would mention this. Anyone else having issues like this? Even if I edit the shared code in Xcode, the function/variable is not recognized. Also, there is no kotlin syntax highlighting in Xcode (not sure if this is possible to acheive), that is why I use IntelliJ b/c the syntax highlighting makes life a lot easier. Using 2 IDE's is probably not the ideal way to go about things. I didn't try doing everything from Xcode. But if developing for multiplatform, eventually you will need at least 2 IDE's if you want to see the app in the emulator. At one point, I had 3 IDE's open (Android Studio, IntelliJ, Xcode) and my laptop crashed. (though I did have a ton of chrome tabs open and other programs running simultaneously). Just thought I'd share my experiences developing multiplat so far. Other than the little inconveniences that I frequently encounter, KMP has been pretty great.

Sam Garfinkel

04/23/2020, 11:00 PM

Is there any idiomatic, first-class analogue for suspendible InputStreams in KMP? I guess you could probably use a flow that emits bytes or something? This library seems like the only option currently: https://github.com/Kotlin/kotlinx-io

mbonnin

04/24/2020, 1:50 PM

Is there something like japicmp for kotlin MPP ? Obsiously it will not be able to work on binaries but maybe at the source level ? Or using metadata ?

SooYoung

04/25/2020, 6:13 AM

Hello. I’m comparing Kotlin MPP to React in terms of testing. While Mockito, Robolectric, Espresso, Hamcrest and Google truth are available for use in Android world, are there any frameworks supporting similar features that can be used to test common code?

Joey

04/26/2020, 5:37 AM

I have the ff gradle

plugins {
    id 'org.jetbrains.kotlin.multiplatform' version '1.3.71'
    id 'org.jetbrains.kotlin.plugin.serialization' version '1.3.71'
}

repositories {
    jcenter()
    mavenCentral()
}

//apply plugin: 'com.android.library'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlinx-serialization'
//android {
//    compileSdkVersion 28
//    buildTypes {
//        release {
//            minifyEnabled false
//        }
//    }
//}

kotlin {
    // This is for iPhone emulator
    // Switch here to iosArm64 (or iosArm32) to build library for iPhone device
    targets {
        final def iOSTarget = System.getenv('SDK_NAME')?.startsWith("iphoneos") \
                          ? presets.iosArm64 : presets.iosX64

        fromPreset(iOSTarget, 'ios') {
            binaries {
                framework("framework")
            }
        }
        fromPreset(presets.jvm, 'android')
    }

    def ktor_version = "1.3.0-rc"
    def serialization_version = "0.14.0"
    def coroutines_version = "1.3.5"
    def klock_version = "1.7.0"

    sourceSets {
        commonMain {
            dependencies {
                implementation kotlin('stdlib-common')
                implementation "io.ktor:ktor-client-core:$ktor_version"
                implementation "org.jetbrains.kotlinx:kotlinx-serialization-runtime-common:$serialization_version"
                implementation "io.ktor:ktor-client-json:$ktor_version"
                implementation("io.ktor:ktor-client-okhttp:$ktor_version")
                implementation "io.ktor:ktor-client-serialization:$ktor_version"
                implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core-common:$coroutines_version"
                implementation "com.soywiz.korlibs.klock:klock:$klock_version"
            }
        }
        commonTest {
            dependencies {
                implementation kotlin('test-common')
                implementation kotlin('test-annotations-common')
            }
        }
        androidMain {
            dependencies {
                implementation kotlin('stdlib')
                implementation "org.jetbrains.kotlinx:kotlinx-serialization-runtime-native:$serialization_version"
                implementation "io.ktor:ktor-client-serialization-jvm:$ktor_version"
            }
        }
        androidTest {
            dependencies {
                implementation kotlin('test')
                implementation kotlin('test-junit')
            }
        }
        iosMain {
            implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core-native:$coroutines_version"
            implementation "io.ktor:ktor-client-serialization-native:$ktor_version"
        }
        iosTest {
            implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core-native:$coroutines_version"
        }
    }
}

// This task attaches native framework built from ios module to Xcode project
// (see iosApp directory). Don't run this task directly,
// Xcode runs this task itself during its build process.
// Before opening the project from iosApp directory in Xcode,
// make sure all Gradle infrastructure exists (gradle.wrapper, gradlew).
task copyFramework {
    def buildType = project.findProperty('kotlin.build.type') ?: 'DEBUG'
    def target = project.findProperty('kotlin.target') ?: 'ios'
    dependsOn kotlin.targets."$target".binaries.getFramework(buildType).linkTask

    doLast {
        def srcFile = kotlin.targets."$target".binaries.getFramework(buildType).outputFile
        def targetDir = getProperty('configuration.build.dir')
        copy {
            from srcFile.parent
            into targetDir
            include 'shared.framework/**'
            include 'shared.framework.dSYM'
        }
    }
}

I also have

enableFeaturePreview("GRADLE_METADATA")

but i couldn't resolve dependencies in my

iosMain

. What am i missing here? Thanks

Davide Giuseppe Farella

04/26/2020, 11:16 AM

I can’t understand why my jvm module (
commandline
) cannot resolve dependencies from other multiplatform modules ( my source code only ) anymore. For example I got a

domain

kotlin {
  jvm()
  js()

  sourceSets {

    val commonMain by getting {
    dependencies {
      api(`kotlin-common`)
      api(`coroutines-core-common`)
     }
    }

    val jvmMain by getting {
      dependencies {
        api(`kotlin-jdk8`)
        api(`coroutines-core`)
      }
    }
    
  }
}

and got

commandline

kotlin {

  sourceSets {

    val main by getting {
    dependencies {
      implementation(project(":domain")
     }
    }
    
  }
}

But it can resolve all the dependencies exposed by

api

in domain ( kotlin, coroutines, koin, etc ), but cannot resolve from my sourceSet ( like

my.project.domain.MyClass

) For some reason it was working before, I think it stopped to work after I added an android module ( which, differently from

commainline

, it’s working flawlessly ) #FYI: I got

enableFeaturePreview("GRADLE_METADATA")

Javier

04/26/2020, 4:50 PM

I am having problems to run test from terminal

Task 'test' not found in root project 'MyRootProject'

, But I can run jvmTest via IntelliJ without problems

Amanjeet Singh

04/27/2020, 5:07 AM

Need a piece of advice, I was writing a repository in

commonMain

using coroutines. Normally, the methods in android would be marked by

suspend

and then they can fetch any data from remote or local. Also writing tests to this on JVM (Android in my case) is easy as we can create a

runBlocking

and assert the results. But when it comes to iOS we don't have any

suspend

methods and thus the same function cannot be tested and thus we end up adding a high order function which will give you an

onSuccess

onFailure

when

launch

coroutine gives result. This seems to be a bit messy to me because in common we end up maintaining 2 implementations for fetching same data each for android and iOS. (common is not "common" anymore in this case) I need an approach which can be directly exposed to both worlds with unit tests also working on both sides. How you guys create repositories and unit test them? Advices and approaches would be appreciated 🙂

➕ 1

Victor Grigorev

04/27/2020, 9:52 AM

Hello! I wanna try to use Periphery (https://github.com/peripheryapp/periphery) static code analyzer in my iOS project, but I get error using Periphery script via the terminal:

Undefined symbols for architecture arm64:

"_OBJC_CLASS_$_IosCombinedDialogModelAlign", referenced from:

objc-class-ref in StringExtensions.o

"_OBJC_CLASS_$...

...

ld: symbol(s) not found for architecture arm64

clang: error: linker command failed with exit code 1 (use -v to see invocation)

What I need to do?

Sean Keane

04/27/2020, 2:45 PM

Hi All! I have a project where im building for Android , iOS and JS and I'm wondering what is the best time library to use for all three platforms? I tried Klock but it gives me JS issues.

ZabGo

04/27/2020, 3:09 PM

I am trying Kotlin Multiplatform on a Mac to develop an iOS app. I cannot access UIDevice, I get “unresolved reference: UIDevice”. Does someone have any idea where the issue could come from? I am maybe missing something in my gradle config. The android studio kotlin plugin has the version 1.3.72. Thanks in advance for your help! Here my gradle files Build.gradle (project)

buildscript {
  ext.kotlin_version = '1.3.72'
  repositories {
    google()
    jcenter()
     
  }
  dependencies {
    classpath 'com.android.tools.build:gradle:3.6.3'
    classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.3.72"



    // NOTE: Do not place your application dependencies here; they belong
    // in the individual module build.gradle files
  }
}

allprojects {
  repositories {
    google()
    jcenter()
     
  }
}

build.gradle(module)

plugins {
  kotlin("multiplatform")
}

Kotlin{
iosX64("ios"){
  binaries {
    framework {
      baseName = "SharedCode"
    }
  }
}

jvm("android")


  sourceSets["commonMain"].dependencies {
    implementation("org.jetbrains.kotlin:kotlin-stdlib-common")
    implementation("io.ktor:ktor-client-core:1.3.2")
    implementation("io.ktor:ktor-client-json:1.3.2")
    implementation("io.ktor:ktor-client-serialization:1.3.2")
  }

  sourceSets["androidMain"].dependencies {
    implementation("org.jetbrains.kotlin:kotlin-stdlib")
    implementation("io.ktor:ktor-client-android:1.3.2")

  }

  sourceSets["iosMain"].dependencies{
    implementation("org.jetbrains.kotlin:kotlin-stdlib")
    implementation("io.ktor:ktor-client-ios:1.3.2")
    implementation("io.ktor:ktor-client-json-native:1.3.2")
    implementation("io.ktor:ktor-client-serialization-native:1.3.2")

  }

}

Shawn Karber_

04/27/2020, 3:24 PM

I am running into some issues I didn't expect porting some Kotlin code that I wrote into Kotlin Multiplatform. It works in a standalone Kotlin app, but not in Kotlin Multiplatform, and I'm assuming they have to be written differently in common.kt? Any suggestions on how to fix these common uses:

fun convertHexToBitString(dataString: String) : String {
            val binaryArray: MutableList<String> = arrayListOf()
            dataString.toCharArray().forEach {
                val binValue =
                    if (it.isDigit()) {
                        String.format("%4s",
                                       Integer.toBinaryString(Character.getNumericValue(it)))
                                       .replace(' ', '0')
                    } else {
                        when(it.toUpperCase()) {
                            'A' -> "1010"
                            'B' -> "1011"
                            'C' -> "1100"
                            'D' -> "1101"
                            'E' -> "1110"
                            'F' -> "1111"
                            else -> "Invalid hexadecimal digit in string."
                        }
                    }
                binaryArray.add(binValue)
            }
            return binaryArray.joinToString("")

it.isDigit() is not working in common.kt, nor is Character.getNumericValue, and neither is String.format(). Are any of these accessible through another means in Kotlin Multiplatform?

Madhan

04/27/2020, 4:08 PM

Hi All, Is it possible to use existing android project for multiplatform project to share my network layer between android and ios.

🇳🇴 2

edenman

04/27/2020, 8:27 PM

anybody already written a common kotlin

val Char.isEmoji: Boolean

helper? The Char api is pretty limited and all my stackoverflow results are jvm or iOS specific

mbonnin

04/27/2020, 11:06 PM

When running macosX64 tests, how can I read a resource file ? Or have access to the test directory, similar to

System.getProperty("user.dir")

on the JVM ?

curioustechizen

04/28/2020, 9:06 AM

I don't know if this should be here or in #kotlin-native but here goes: Is

resumeWith

kotlin.coroutines.Continuation

a mutating operation? If so, how can I share it with another thread in order to bridge callback-style APIs and suspend functions? My scenario: I have a suspend function in a shared API (shared between Android and iOS). On Android I just implement it as a regular suspend function. On iOS, I'm attempting to use

continuation

and call it from my callback. • If I freeze the continuation object I receive

InvalidMutabilityException

, • if I don't freeze it, I receive

IncorrectDereferenceException

. I'm using coroutines 1.3.5-native-mt

Title

curioustechizen

04/28/2020, 9:06 AM

I don't know if this should be here or in #kotlin-native but here goes: Is

resumeWith

kotlin.coroutines.Continuation

continuation

and call it from my callback. • If I freeze the continuation object I receive

InvalidMutabilityException

, • if I don't freeze it, I receive

IncorrectDereferenceException

. I'm using coroutines 1.3.5-native-mt

I receive these exceptions at the point that I call

continution.resumeWith

in my Swift code

For anyone interested in this, with coroutines 1.3.5-native-mt this does not work. I ended up using coroutines-worker library from Autodesk to get this to Work

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