fix: black screen on scan on iOS

sample-app/shared/src/commonMain/kotlin/MainView.kt

@@ -16,10 +16,15 @@ import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
+import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
 import org.publicvalue.multiplatform.qrcode.CameraPosition
 import org.publicvalue.multiplatform.qrcode.CodeType
 import org.publicvalue.multiplatform.qrcode.ScannerWithPermissions
+import kotlin.time.Duration.Companion.minutes
+import kotlin.time.Duration.Companion.seconds
+import kotlin.time.TimeMark
+import kotlin.time.TimeSource
 
 @Composable
 fun MainView() {
@@ -39,14 +44,27 @@ fun MainView() {
             }) {
                 Text("Toggle scanner (visible: $scannerVisible)")
             }
+            var lastCode by remember { mutableStateOf<String?>(null)}
+            var snackbarJob by remember { mutableStateOf<Job?>(null)}
+            var lastSnackbar by remember { mutableStateOf(TimeSource.Monotonic.markNow().minus(1.minutes))}
             if (scannerVisible) {
                 val scope = rememberCoroutineScope()
                 ScannerWithPermissions(
                     modifier = Modifier.padding(16.dp),
                     onScanned = {
-                        scope.launch {
+                        if (lastCode == it) { return@ScannerWithPermissions false }
+                        if (TimeSource.Monotonic.markNow().minus(lastSnackbar) < 1.seconds) {
+                            return@ScannerWithPermissions false
+                        }
+                        snackbarJob?.cancel()
+                        lastSnackbar = TimeSource.Monotonic.markNow()
+                        snackbarJob = scope.launch {
                             snackbarHostState.showSnackbar(it, duration = SnackbarDuration.Short)
+                            if (lastCode == it) {
+                                lastCode = null
+                            }
                         }
+                        lastCode = it
                         false // continue scanning
                     },
                     types = listOf(CodeType.QR),

scanner/src/iosMain/kotlin/ScannerView.kt

@@ -197,7 +197,6 @@ class ScannerCameraCoordinator(
         }
     }
 
-
     fun setCurrentOrientation(newOrientation: UIDeviceOrientation) {
         when(newOrientation) {
             UIDeviceOrientation.UIDeviceOrientationLandscapeLeft ->
@@ -219,11 +218,9 @@ class ScannerCameraCoordinator(
     }
 
     fun onFound(code: String) {
-        captureSession.stopRunning()
-        if (!onScanned(code)) {
-            GlobalScope.launch(Dispatchers.Default) {
-                captureSession.startRunning()
-            }
+        val stopScanning = onScanned(code)
+        if (stopScanning) {
+            captureSession.stopRunning()
         }
     }