Lightweight library for seamless cross-platform message display in apps, offering custom Snackbar UI, toast messages, alert dialogs with shared API, custom actions, and duration control.
Compose CrossMessages shows snackbars, toasts and alert dialogs from a single Compose Multiplatform codebase, using each platform's own presentation where it matters.
| Snackbar | Toast | Alert | |
|---|---|---|---|
| Android | Material 3 Compose | android.widget.Toast | Material 3 AlertDialog |
| iOS | Material 3 Compose | UIKit overlay | UIAlertController |
| Desktop (JVM) | Material 3 Compose | Compose surface | Material 3 AlertDialog |
| Web (wasmJs / js) | Material 3 Compose | Compose surface | Material 3 AlertDialog |
dependencies {
implementation("io.github.berkaykirecci:crossmessages:2.0.0")
}
Published targets: android, iosArm64, iosSimulatorArm64, jvm, wasmJs, js.
iOS:
iosX64is not published. Compose Multiplatform dropped it in 1.11.0, so the iOS simulator on Intel Macs is unsupported — device builds and Apple Silicon simulators are unaffected.Kotlin/JS: the Compose JS canvas target is still experimental upstream, so add
org.jetbrains.compose.experimental.jscanvas.enabled=trueto yourgradle.properties.wasmJsneeds no flag.
Place the hosts as the last children of a full-size container so they overlay your content:
@Composable
fun App() {
val snackbarHostState = rememberCrossSnackbarHostState()
val toastHostState = rememberCrossToastHostState()
val alertHostState = rememberCrossAlertHostState()
Box(Modifier.fillMaxSize()) {
MyScreen(snackbarHostState)
CrossSnackbarHost(snackbarHostState)
CrossToastHost(toastHostState)
CrossAlertHost(alertHostState)
}
}
Each one picks a palette derived from your MaterialTheme and a matching leading icon.
snackbarHostState.success("Saved to your library")
snackbarHostState.warning("Storage almost full")
snackbarHostState.error("Upload failed")
snackbarHostState.info("Syncing in the background")
The suspending overload returns the outcome, which is the point of having an action at all:
scope.launch {
val result = snackbarHostState.showSnackbar(
message = "Message archived",
actionLabel = "Undo",
duration = CrossSnackbarDuration.Long,
)
if (result == CrossSnackbarResult.ActionPerformed) {
unarchive()
}
}
snackbarHostState.show(
CrossSnackbarVisuals(
message = "Custom message",
actionLabel = "Retry",
withDismissAction = true,
duration = CrossSnackbarDuration.Indefinite,
position = CrossSnackbarPosition.Top,
style = CrossSnackbarStyle.Warning,
icon = CrossSnackbarIcon.Resource(Res.drawable.my_icon),
colors = CrossSnackbarColors(
containerColor = Color(0xFF0F5132),
contentColor = Color(0xFFD1FADF),
actionColor = Color(0xFF6EE7A0),
),
textAlign = TextAlign.Center,
dismissActionContentDescription = "Close notification",
)
)
CrossSnackbarDuration is Short (~4s), Long (~10s) or Indefinite. All three are widened to
the platform's recommended accessibility timeout when the user has asked for more time.
CompositionLocalProvider(
LocalCrossSnackbarColors provides CrossSnackbarStyleColors(
success = CrossSnackbarColors(Color(0xFF0F5132), Color(0xFFD1FADF)),
)
) {
CrossSnackbarHost(snackbarHostState)
}
Entries left null keep the theme-derived default. CrossSnackbarStyle.Error maps onto
colorScheme.errorContainer, and the neutral style onto inverseSurface, so a custom color scheme
carries through without any configuration.
CrossSnackbarHost(snackbarHostState) { data ->
MyOwnSnackbar(data.visuals.message, onDismiss = data::dismiss)
}
toastHostState.show("Toast message")
toastHostState.show("Longer toast", CrossToastDuration.Long)
CrossToastHost defaults to CrossToastStyle.Native — android.widget.Toast on Android, a UIKit
overlay on iOS, and the shared Compose surface on desktop and web. Pass
CrossToastStyle.Compose to get the identical Compose surface on every platform:
CrossToastHost(toastHostState, style = CrossToastStyle.Compose)
scope.launch {
val result = alertHostState.showAlert(
CrossAlertVisuals(
title = "Delete draft?",
message = "This cannot be undone.",
actions = persistentListOf(
CrossAlertAction("Cancel", CrossAlertActionStyle.Cancel),
CrossAlertAction("Delete", CrossAlertActionStyle.Destructive),
),
)
)
if (result is CrossAlertResult.ActionPerformed && result.index == 1) {
deleteDraft()
}
}
Any number of actions is supported. CrossAlertActionStyle.Destructive renders in
colorScheme.error on Compose platforms and maps to UIAlertActionStyleDestructive on iOS.
Passing no actions at all yields a single confirm button labelled defaultConfirmLabel.
CrossAlertVisuals.actions is an ImmutableList so the Compose compiler can infer its stability
rather than take an @Immutable promise. kotlinx-collections-immutable arrives transitively, so
import kotlinx.collections.immutable.persistentListOf works without declaring anything extra. If
you'd rather pass a plain List, use the convenience overload, which converts for you:
alertHostState.show(
title = "Delete draft?",
message = "This cannot be undone.",
actions = listOf(
CrossAlertAction("Cancel", CrossAlertActionStyle.Cancel),
CrossAlertAction("Delete", CrossAlertActionStyle.Destructive),
),
)
The sample exercises every API — all snackbar styles, positions, queueing, the suspending result flow, both toast styles, and alerts with one, two and three actions.
It is split in two: :sample holds the shared Compose UI and the desktop/iOS/web entry points,
while :sample-android is a thin Android launcher. They are separate because AGP 9 no longer allows
com.android.application in a Kotlin Multiplatform module.
./gradlew :sample-android:installDebug # Android
./gradlew :sample:run # Desktop
./gradlew :sample:wasmJsBrowserDevelopmentRun # Web
open iosApp/iosApp.xcodeproj # iOS — then hit Run
The iOS app lives in iosApp/. A build phase invokes
:sample:embedAndSignAppleFrameworkForXcode, which links the SampleKit framework and copies the
Compose resources into the app bundle, so Xcode is the only thing you need. From the command line:
xcodebuild -project iosApp/iosApp.xcodeproj -scheme iosApp \
-destination 'generic/platform=iOS Simulator' build
Building for a physical device additionally needs your Apple Developer Team ID in
iosApp/Configuration/Config.xcconfig; the simulator needs no signing.
2.0 is a clean break. Everything now lives under io.github.berkaykirecci.crossmessages.* instead
of the top-level model / state / ui / platform packages — the old package shadowed
Kotlin/Native's own namespace, and collided with
.
Behavioural changes worth knowing about:
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless applicable law agreed to writing, software
distributed under the License distributed an BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express implied.
See the License the specific language governing permissions
limitations under the License.
Pull requests and issues are welcome!
showSnackbar(...) returns a CrossSnackbarResult, so you learn whether
the user tapped your action or let it time out — no callback plumbing.Mutex, so repeating the same text queues
correctly and nothing is dropped or dequeued out of order.MaterialTheme and follow its light/dark switch. Nothing is hard-coded to white or black.IconButton, and durations stretch to the platform's recommended accessibility
timeout.platformplatform.*model.SnackbarDefaultsandroidx.compose.material3.SnackbarDefaults| 1.x | 2.0 |
|---|
MultiPlatformSnackbar(state = s) | CrossSnackbarHost(hostState = s) |
Toast(state = s) | CrossToastHost(hostState = s) |
Alert(state = s) | CrossAlertHost(hostState = s) |
rememberSnackbarState() | rememberCrossSnackbarHostState() |
rememberToastState() | rememberCrossToastHostState() |
rememberAlertState() | rememberCrossAlertHostState() |
SnackbarModel | CrossSnackbarVisuals |
LeadingIconModel / TextModel / ActionButtonModel | folded into CrossSnackbarVisuals + CrossSnackbarColors |
duration = 3000L | duration = CrossSnackbarDuration.Long |
alignment = Alignment.TopCenter | position = CrossSnackbarPosition.Top |
backgroundColor + textModel.textColor | colors = CrossSnackbarColors(container, content) |
showActionButton + actionButtonModel | withDismissAction + actionLabel |
LocalSnackbarColors / DefaultSnackbarColors | LocalCrossSnackbarColors / CrossSnackbarStyleColors |
AlertModel(message, title, actions) | CrossAlertVisuals(title, message, actions) |
DialogAction(actionTitle, style, callbak) | CrossAlertAction(label, style, onClick) |
ActionStyle.DEFAULT / .CANCEL / .DESTRUCTIVE | CrossAlertActionStyle.Default / .Cancel / .Destructive |
state.clear() | state.dismissCurrent() |
platform.getViewController() | removed — internal |
Toast.makeText().show() and
presentViewController from the composable body, so recomposition duplicated them.DEFAULT and first CANCEL, and always
drew a dismiss button — blank when there was no cancel action.Surfaced from shared tags and platforms — no rankings paid for.