Show bottom-bar only when current-destination is TopLevel.

app/src/main/java/com/google/samples/apps/nowinandroid/navigation/NiaTopLevelNavigation.kt

@@ -22,6 +22,7 @@ import androidx.compose.material.icons.filled.Upcoming
 import androidx.compose.material.icons.outlined.Grid3x3
 import androidx.compose.material.icons.outlined.Upcoming
 import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.navigation.NavDestination
 import androidx.navigation.NavGraph.Companion.findStartDestination
 import androidx.navigation.NavHostController
 import com.google.samples.apps.nowinandroid.feature.foryou.R.string.for_you
@@ -78,3 +79,15 @@ val TOP_LEVEL_DESTINATIONS = listOf(
         iconTextId = interests
     )
 )
+
+/**
+ * @return true when the current destination is
+ * top level destination else false.
+ */
+fun NavDestination?.isTopLevelDestination(): Boolean {
+    return when (this?.route) {
+        ForYouDestination.route -> true
+        InterestsDestination.route -> true
+        else -> false
+    }
+}

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaApp.kt

@@ -59,6 +59,7 @@ import com.google.samples.apps.nowinandroid.navigation.NiaNavHost
 import com.google.samples.apps.nowinandroid.navigation.NiaTopLevelNavigation
 import com.google.samples.apps.nowinandroid.navigation.TOP_LEVEL_DESTINATIONS
 import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination
+import com.google.samples.apps.nowinandroid.navigation.isTopLevelDestination
 
 @OptIn(ExperimentalMaterial3Api::class, ExperimentalLayoutApi::class)
 @Composable
@@ -79,10 +80,12 @@ fun NiaApp(windowSizeClass: WindowSizeClass) {
                 contentColor = MaterialTheme.colorScheme.onBackground,
                 bottomBar = {
                     if (windowSizeClass.widthSizeClass == WindowWidthSizeClass.Compact) {
-                        NiABottomBar(
-                            onNavigateToTopLevelDestination = niaTopLevelNavigation::navigateTo,
-                            currentDestination = currentDestination
-                        )
+                        if (currentDestination.isTopLevelDestination()) {
+                            NiABottomBar(
+                                onNavigateToTopLevelDestination = niaTopLevelNavigation::navigateTo,
+                                currentDestination = currentDestination
+                            )
+                        }
                     }
                 }
             ) { padding ->