How to create Toast message in CMP Compose MultiPlatform | Android and iOS

How to create a toast message using Compose Multiplatform (CMP)

Output

In Kotlin Multiplatform (KMP), you typically cannot call platform-specific features like Toast messages directly from the commonMain module. However, you can achieve this by defining an expect function or class in commonMain that acts as an abstraction. Then, implement the corresponding actual functionality in the androidMain and iosMain modules.

Here’s how to set this up step-by-step:

Step 1: Define an Expect Function in Common Code

In your shared commonMain module, define an expect function for showing a toast. This acts as a placeholder for the actual implementation on each platform.

commonMain

Create a new class ToastManager

// commonMain/kotlin/ToastManager.kt
expect open class ToastManager() {
    fun showToast(message: String)
}

Note: TostManager class gives an error. You need to import classes for Android and iOS. Right click to fix. It will automatically create two classes ToastManager.ios.kt and ToastManager.android.kt.

Edit the autogenerated classes.