Mastering Dependencies in Kotlin Multiplatform

In this presentation, we'll dive deep into the Kotlin Multiplatform Plugin's dependency management system and explore strategies for handling both KMP-specific and platform-specific libraries. We'll also provide solutions to common Cocoapods-related issues. By the end, you'll have the skills to manage dependencies like a pro and build successful Kotlin Multiplatform applications.

Transcript

1. Kotlin Budapest Meetup I 2024 Tamas Fabian Principal Android Software Engineer October 17, 2024 Mastering Dependencies in Kotlin Multiplatform
2. Kotlin Budapest Meetup I 2024 Agenda 1. Story time 2. Basics 3. Dependencies in Kotlin Multiplatform 4. Platform-specific deps 5. Common issues
3. Kotlin Budapest Meetup I 2024 Story time
4. Kotlin Budapest Meetup I 2024 The Project The company's chat application is in need of an overhaul. Two principal Native Mobile Developers got hired. Options: - Refactor - Reimplement native apps - Or... guess what?
5. Kotlin Budapest Meetup I 2024
6. Kotlin Budapest Meetup I 2024 Basics
7. Kotlin Budapest Meetup I 2024 Basics commonMain nativeMain androidNativeMain appleMain iosMain iosArm64Main iosSimulatorArm64M ain macosMain tvosMain watchosMain linuxMain mingwMain androidMain jvmMain compilation main .classfiles jsMain compilation test .classfiles commonTest jvmTest compilation main .js jsTest compilation test .js nativeTest androidNativeTest appleTest iosTest iosArm64Test iosSimulatorArm64T est macosTest tvosTest watchosTest linuxTest mingwTest androidTest jvm target js target
8. Kotlin Budapest Meetup I 2024 Part of the build responsible for compiling, testing, and packaging a piece of software targeting one of the supported platforms. • Presets for supported platforms Targets Basics kotlin { applyDefaultHierarchyTemplate() androidTarget() iosX64(), iosArm64(), iosSimulatorArm64() }
9. Kotlin Budapest Meetup I 2024 Part of the build responsible for compiling, testing, and packaging a piece of software targeting one of the supported platforms. • Presets for supported platforms Targets Basics kotlin { applyDefaultHierarchyTemplate() androidTarget() iosX64(), iosArm64(), iosSimulatorArm64() }
10. Kotlin Budapest Meetup I 2024 Part of the build responsible for compiling, testing, and packaging a piece of software targeting one of the supported platforms. • Presets for supported platforms Targets Basics kotlin { applyDefaultHierarchyTemplate { common { group("posix") { withLinux() withMingw() withMacos() } } }
11. Kotlin Budapest Meetup I 2024 Part of the build responsible for compiling, testing, and packaging a piece of software targeting one of the supported platforms. • Presets for supported platforms • Common & Target-specific configurations Targets Basics kotlin { androidTarget { @OptIn(ExperimentalKotlinGradlePluginApi::class) compilerOptions { jvmTarget.set(JvmTarget.JVM_11) } } }
12. Kotlin Budapest Meetup I 2024 Part of the build responsible for compiling, testing, and packaging a piece of software targeting one of the supported platforms. • Presets for supported platforms • Common & Target-specific configurations Targets Basics kotlin { listOf( iosX64(), iosArm64(), iosSimulatorArm64() ).forEach { iosTarget -> iosTarget.binaries.framework { baseName = "Shared" isStatic = true } } }
13. Kotlin Budapest Meetup I 2024 Part of the build responsible for compiling, testing, and packaging a piece of software targeting one of the supported platforms. • Presets for supported platforms • Common & Target-specific configurations • One or more compilations Targets Basics
14. Kotlin Budapest Meetup I 2024 Compilations are used for defining the way how final artifacts are produced. • JVM, JS, Native: main & test Compilations Basics kotlin { jvm { val main by compilations.getting { compilerOptions.configure { jvmTarget.set(JvmTarget.JVM_17) } } } }
15. Kotlin Budapest Meetup I 2024 Compilations are used for defining the way how final artifacts are produced. • JVM, JS, Native: main & test • Android: by build variants Compilations Basics kotlin { jvm { val main by compilations.getting { compilerOptions.configure { jvmTarget.set(JvmTarget.JVM_17) } } } }
16. Kotlin Budapest Meetup I 2024 A source set is a set of source files with its own targets, dependencies, and compiler options. It's the main way to share code in multiplatform projects. • Unique name • Predefined source sets • commonMain • <targetName><compilationName> SourceSets Basics sourceSets { commonMain.dependencies { //put your multiplatform dependencies here } commonTest.dependencies { implementation(libs.kotlin.test) } }
17. Kotlin Budapest Meetup I 2024 A source set is a set of source files with its own targets, dependencies, and compiler options. It's the main way to share code in multiplatform projects. • Unique name • Predefined source sets • commonMain • <targetName><compilationName> SourceSets Basics sourceSets { commonMain.dependencies { implementation(libs.kotlinx.coroutines.core) } jsMain.dependencies { implementation(libs.kotlinx.coroutines.core-js) } }
18. Kotlin Budapest Meetup I 2024 A source set is a set of source files with its own targets, dependencies, and compiler options. It's the main way to share code in multiplatform projects. • Unique name • Predefined source sets • commonMain • <targetName><compilationName> • Intermediate source sets SourceSets Basics sourceSets { val commonJvm by creating { dependsOn(commonMain.get()) dependencies { implementation(libs.socketIo) } } androidMain { dependsOn(commonJvm) } jvmMain { dependsOn(commonJvm) } }
19. Kotlin Budapest Meetup I 2024 A source set is a set of source files with its own targets, dependencies, and compiler options. It's the main way to share code in multiplatform projects. • Unique name • Predefined source sets • commonMain • <targetName><compilationName> • Intermediate source sets • DSL reference SourceSets Basics
20. Kotlin Budapest Meetup I 2024 Basics commonMain nativeMain androidNativeMain appleMain iosMain iosArm64Main iosSimulatorArm64M ain macosMain tvosMain watchosMain linuxMain mingwMain androidMain jvmMain compilation main .classfiles jsMain compilation test .classfiles commonTest jvmTest compilation main .js jsTest compilation test .js nativeTest androidNativeTest appleTest iosTest iosArm64Test iosSimulatorArm64T est macosTest tvosTest watchosTest linuxTest mingwTest androidTest jvm target js target
21. Kotlin Budapest Meetup I 2024 Dependencies in Kotlin Multiplatform
22. Kotlin Budapest Meetup I 2024 You can set them at: • Source set level api, implementation, compileOnly, runtimeOnly Dependencies in Kotlin Multiplatform sourceSets { commonMain.dependencies { implementation(libs.kotlinx.coroutines.core) } jsMain.dependencies { implementation(libs.kotlinx.coroutines.core-js) } }
23. Kotlin Budapest Meetup I 2024 You can set them at: • Source set level • Top level api, implementation, compileOnly, runtimeOnly Dependencies in Kotlin Multiplatform dependencies { commonMainImplementation(libs.kotlinx.coroutines.core) jsMainImplementation(libs.kotlinx.coroutines.core-js) }
24. Kotlin Budapest Meetup I 2024 You can set them at: • Source set level • Top level You can add dependencies on: • Kotlin library api, implementation, compileOnly, runtimeOnly Dependencies in Kotlin Multiplatform sourceSets { commonMain.dependencies { implementation(kotlin("stdlib")) } commonTest.dependencies { implementation(kotlin("test")) } }
25. Kotlin Budapest Meetup I 2024 You can set them at: • Source set level • Top level You can add dependencies on: • Kotlin library api, implementation, compileOnly, runtimeOnly Dependencies in Kotlin Multiplatform sourceSets { commonMain.dependencies { implementation(kotlin("stdlib")) } commonTest.dependencies { implementation(kotlin("test")) } }
26. Kotlin Budapest Meetup I 2024 You can set them at: • Source set level • Top level You can add dependencies on: • Kotlin library • Kotlin Multiplatform library api, implementation, compileOnly, runtimeOnly Dependencies in Kotlin Multiplatform sourceSets { commonMain.dependencies { implementation(libs.kotlinx.serialization.json) } }
27. Kotlin Budapest Meetup I 2024 You can set them at: • Source set level • Top level You can add dependencies on: • Kotlin library • Kotlin Multiplatform library • Platform-specific library api, implementation, compileOnly, runtimeOnly Dependencies in Kotlin Multiplatform sourceSets { androidMain.dependencies { implementation(libs.retrofit) } }
28. Kotlin Budapest Meetup I 2024 You can set them at: • Source set level • Top level You can add dependencies on: • Kotlin library • Kotlin Multiplatform library • Platform-specific library • Kotlin Multiplatform project api, implementation, compileOnly, runtimeOnly Dependencies in Kotlin Multiplatform sourceSets { commonMain.dependencies { api(projects.core) } }
29. Kotlin Budapest Meetup I 2024 • Compatible targets • Versions are aligned through source sets Dependency resolution Dependencies in Kotlin Multiplatform
30. Kotlin Budapest Meetup I 2024 • Compatible targets • Versions are aligned through source sets Dependency resolution Dependencies in Kotlin Multiplatform kermit:2.0.0 commonMain kermit:2.0.0 androidMain kermit:2.0.0 iosMain
31. Kotlin Budapest Meetup I 2024 • Compatible targets • Versions are aligned through source sets Dependency resolution Dependencies in Kotlin Multiplatform kermit:2.0.0 commonMain kermit:2.0.0 kermit:2.0.4 anAndroidLibrary:1.0.0 androidMain kermit:2.0.0 iosMain
32. Kotlin Budapest Meetup I 2024 • Compatible targets • Versions are aligned through source sets Dependency resolution Dependencies in Kotlin Multiplatform kermit:2.0.0 kermit:2.0.4 commonMain kermit:2.0.0 kermit:2.0.4 anAndroidLibrary:1.0.0 androidMain kermit:2.0.0 kermit:2.0.4 iosMain
33. Kotlin Budapest Meetup I 2024 Platform-specific dependencies
34. Kotlin Budapest Meetup I 2024 • The same Android Platform-specific dependencies sourceSets { androidMain.dependencies { implementation(libs.androidx.lifecycle.viewmodel) } }
35. Kotlin Budapest Meetup I 2024 • npm() function Kotlin/JS Platform-specific dependencies sourceSets { jsMain.dependencies { implementation(npm(“is-sorted”, ”1.0,5”)) } }
36. Kotlin Budapest Meetup I 2024 • npm() function • External declarations Kotlin/JS Platform-specific dependencies @JsModule("is-sorted") @JsNonModule external fun <T> sorted(a: Array<T>): Boolean
37. Kotlin Budapest Meetup I 2024 • Definition file .def • Properties Kotlin/Native Platform-specific dependencies headers = curl/curl.h headerFilter = curl/* compilerOpts.linux = -I/usr/include -I/usr/include/x86_64-linux-gnu linkerOpts.osx = -L/opt/local/lib -L/usr/local/opt/curl/lib -lcurl linkerOpts.linux = -L/usr/lib/x86_64-linux-gnu -lcurl
38. Kotlin Budapest Meetup I 2024 • Cocoapods • (SPM) iOS Platform-specific dependencies cocoapods { summary = "Some description for the Shared Module" homepage = "Link to the Shared Module homepage" version = "1.0" ios.deploymentTarget = "16.0" podfile = project.file("../iosApp/Podfile") framework { baseName = "shared" isStatic = true } pod("FirebaseAuth") { version = "10.16.0" } }
39. Kotlin Budapest Meetup I 2024 • Cocoapods • cinterop iOS Platform-specific dependencies MyFramework.def language = Objective-C modules = MyFramework package = MyFramework
40. Kotlin Budapest Meetup I 2024 • Cocoapods • cinterop iOS Platform-specific dependencies iosArm64 { val main by compilations.getting { val MyFramework by cinterops.creating { definitionFile.set(project.file("src/nativeInterop/cinterop/MyFramework.def")) compilerOpts("-framework", "MyFramework", "-F/path/to/framework/") } } binaries.all { linkerOpts("-framework", "MyFramework", "-F/path/to/framework/") } }
41. Kotlin Budapest Meetup I 2024 Common issues
42. Kotlin Budapest Meetup I 2024 cocoapods { pod("Socket.IO-Client-Swift") { version = "16.1.1” moduleName = "SocketIO" } } Swift-only library Common Issues :shared:iosArm64Main: cinterop file: /Users/tfabian/AndroidStudioProjects/Couchbase/shared/build/c lasses/kotlin/iosArm64/main/cinterop/ shared-cinterop-SocketIO.klib does not exist Possible solution: - Declare repository providing the artifact, see the documentation at https://docs.gradle.org/current/userguide/declaring_repositories .html Error
43. Kotlin Budapest Meetup I 2024 cocoapods { pod("Socket.IO-Client-Swift") { version = "16.1.1” moduleName = "SocketIO" } } Swift-only library Common Issues @objc public class SocketIo: NSObject { @objc public func connect() { socket.connect() } @objc public func disconnect() { socket.disconnect() } ... } Solution
44. Kotlin Budapest Meetup I 2024 sourceSets { commonMain.dependencies { api(libs.kotlinx.serialization.json) } } Transitive dependencies Common Issues java.lang.NoClassDefFoundError: Failed resolution of: Lkotlinx/serialization/json/JsonKt Error
45. Kotlin Budapest Meetup I 2024 sourceSets { commonMain.dependencies { api(libs.kotlinx.serialization.json) } } Transitive dependencies Common Issues kotlin { ios.binaries.framework { export(libs.kotlinx.serialization.json) // OR transitiveExport = true } } Solution
46. Kotlin Budapest Meetup I 2024 cocoapods { pod("Socket.IO-Client-Swift") { version = "16.1.1” moduleName = "SocketIO" } } @import directives Common Issues Exception in thread "main" java.lang.Error: /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSi mulator18.0.sdk/usr/include/copyfile.h:35:10: fatal error: 'sys/cdefs.h' file not found … /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSi mulator18.0.sdk/System/Library/Frameworks/CFNetwork.framework/Headers/CFNetwork.h:18:10: fatal error: could not build module 'CoreFoundation’ /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSi mulator18.0.sdk/usr/include/xpc/xpc.h:6:10: fatal error: could not build module 'os_object’ at org.jetbrains.kotlin.native.interop.indexer.ModuleSupportKt.getModulesASTFiles(ModuleSupport.kt:80) at org.jetbrains.kotlin.native.interop.indexer.ModuleSupportKt.getModulesInfo(ModuleSupport.kt:15) at org.jetbrains.kotlin.native.interop.gen.jvm.MainKt.buildNativeLibrary(main.kt:564) at org.jetbrains.kotlin.native.interop.gen.jvm.MainKt.processCLib(main.kt:308) at org.jetbrains.kotlin.native.interop.gen.jvm.MainKt.processCLibSafe(main.kt:244) at org.jetbrains.kotlin.native.interop.gen.jvm.MainKt.access$processCLibSafe(main.kt:1) at org.jetbrains.kotlin.native.interop.gen.jvm.Interop.interop(main.kt:102) at org.jetbrains.kotlin.cli.utilities.InteropCompilerKt.invokeInterop(InteropCompiler.kt:49) at org.jetbrains.kotlin.cli.utilities.MainKt.mainImpl(main.kt:23) at org.jetbrains.kotlin.cli.utilities.MainKt.main(main.kt:44) Error
47. Kotlin Budapest Meetup I 2024 cocoapods { pod("Socket.IO-Client-Swift") { version = "16.1.1” moduleName = "SocketIO" } } @import directives Common Issues extraOpts += listOf("-compiler-option", "-fmodules") Solution
48. Kotlin Budapest Meetup I 2024 cocoapods { pod("Socket.IO-Client-Swift") { version = "16.1.1” } } Dash in cocoapod’s name Common Issues fatal error: module 'socket_io_wrapper' not found Error
49. Kotlin Budapest Meetup I 2024 cocoapods { pod("Socket.IO-Client-Swift") { version = "16.1.1” } } Dash in cocoapod’s name Common Issues moduleName = "SocketIO" Solution
50. Kotlin Budapest Meetup I 2024 cocoapods { pod("StripePaymentsUI") { version = ”23.31.1" } } Pod::Spec.new do |s| s.name = 'StripePaymentsUI’ ... s.dependency 'StripeCore', s.version.to_s s.dependency 'StripeUICore', s.version.to_s s.dependency 'StripePayments', s.version.to_s end Linked modules Common Issues Unresolved reference: STPPaymentHandlerActionStatus Error
51. Kotlin Budapest Meetup I 2024 cocoapods { pod("StripePaymentsUI") { version = ”23.31.1" } } Linked modules Common Issues pod("StripePayments") { version = ”23.31.1" } Solution
52. Kotlin Budapest Meetup I 2024 sourceSets { commonMain.dependencies { implementation(libs.google.gson) } } Dependency at the wrong place Common Issues Nothing :( Error
53. Kotlin Budapest Meetup I 2024 sourceSets { commonMain.dependencies { implementation(libs.google.gson) } } Dependency at the wrong place Common Issues androidMain • Remember what you’ve learned. • KT-72287 Improve error reporting when dependency doesn't match expected platforms Solution
54. Kotlin Budapest Meetup I 2024 Libraries’ libraries
55. Kotlin Budapest Meetup I 2024 Libraries’ libraries
56. Kotlin Budapest Meetup I 2024 Libraries’ libraries
57. Kotlin Budapest Meetup I 2024 Libraries’ libraries
58. Kotlin Budapest Meetup I 2024 Libraries’ libraries
59. Kotlin Budapest Meetup I 2024 Thank you.
60. Kotlin Budapest Meetup. I 2024 Get in Touch LinkedIn in/tamas--fabian X @tomi_fabian GitHub github.com/TomiFabian
61. Kotlin Budapest Meetup I 2024 • https://kotlinlang.org/docs/multiplatform-intro.html • https://github.com/JetBrains/kotlin • https://github.com/JakeWharton/mosaic • https://stackoverflow.com/questions/tagged/kotlin-multiplatform • https://youtrack.jetbrains.com/issues/KT References