Any proper way of handling backpress in compose mu...

# compose

[Shubham Pathak2000]

Any proper way of handling backpress in compose multiplatform?

[Tim Karagosian]

I'm thinking you'll need an expect/actual to handle this. You'll should just need to override the OnBackPressed for Android and dismiss() for iOS.

I'm not sure if there's a library yet for this functionality, but it would probably be nice to have if there isn't.

[Shubham Pathak2000]

read about BackHandler class in CMP but it's not working lol

[Tim Karagosian]

I unfortunately haven’t had a use case for it so I was only going by some quick research. This is some code from chat GPT:

// androidMain
private var backCallback: OnBackPressedCallback? = null

actual fun registerBackHandler(onBack: () -> Unit) {
val activity = currentActivity ?: return
backCallback = object : OnBackPressedCallback(true) {
override fun handleOnBackPressed() {
onBack()
}
}
activity.onBackPressedDispatcher.addCallback(backCallback!!)
}

actual fun unregisterBackHandler() {
backCallback?.remove()
backCallback = null
}

// Helper to get current activity (can vary depending on your setup)
val currentActivity: ComponentActivity?
get() = /* your Activity reference retrieval logic */

So you have the setup for some expect/actuals. The ios side will need a tie into gestures and pops.

Alternatively to all this, the navigation library Decompose has a built in onBackPressed method that you can use for its behavior in the simplest way possible. I use Decompose and love it as it’s very feature rich and has a lot of common uses solutioned.

[mattinger]

I think the main thing here to remember is that a "back button" is not universal. Sure it exists on android as soft button or a gesture, and it exists on iOS as a gesture as well. But what about desktop? There's really no concept of a "back" in desktop. As such i think an expect actual as people have suggested above is your best bet, and to the right thing for each platform you support.

[Arkadii Ivanov]

On desktop we have the Esc button, or whatever you want to use as back. Should be easy to bind with Decompose, not sure about other libs.

[Vidmantas Kerbelis]

If you add:

implementation("org.jetbrains.compose.ui:ui-backhandler:1.8.0-alpha03")

BackHandler + PredictiveBackHandler will become present in the commonMain source

[Shubham Pathak2000]

@Vidmantas Kerbelis tried that but didn;t work at all on iOS, not sure if we need to integrate in a different way for both platforms.. i just added backhandler(predictive =true) { navcomtroller.pop() } in the root compose