CMP/KMP iOS build failed with "No matching variant of androidx.compose.foundation:foundation:1.7.0.."

Please share your build.gradle file if you need more help. I expect this is coming from pre-compile build phase in your xcode project that builds the KMP part of your app via Gradle (which is standard setup in KMP projects).

Google does not publish the compose multiplatform artifacts for non-android platforms. To use Compose Multiplatform, your build.gradle should look something like this: https://github.com/Kotlin/KMP-App-Template/blob/main/composeApp/build.gradle.kts.

In particular, you need to apply these plugins:

plugins {
  alias(libs.plugins.kotlinMultiplatform)
  alias(libs.plugins.androidApplication)
  alias(libs.plugins.composeMultiplatform)
  alias(libs.plugins.composeCompiler)
}

And instead of depending on the androidx artifacts directly, declare your dependencies like so:

commonMain.dependencies {
  implementation(compose.runtime)
  implementation(compose.foundation)
  ...
}

For posterity, the .toml file declares the exact plugin coordinates:

androidApplication = { id = "com.android.application", version.ref = "agp" }
composeCompiler = { id = "org.jetbrains.kotlin.plugin.compose", version.ref = "kotlin" }
composeMultiplatform = { id = "org.jetbrains.compose", version.ref = "compose-multiplatform" }
kotlinMultiplatform = { id = "org.jetbrains.kotlin.multiplatform", version.ref = "kotlin" }

After some digging, this appears to be an issue when using non-KMP dependencies in the commonMain.dependencies block. In my case, I was using koin-androidx-compose-navigation, which is an Android-only dependency. That will produce this (unhelpful) error.

To get rid of it, I removed dependencies one-by-one until I figured out what the root cause was.