🐛 [iOS] Present the camera from a dedicated window by default

When no explicit presenter is supplied, openCameraPicker used to present
the fullscreen UIImagePickerController from the top-most view controller
of the main window. Hosts whose dialogs live in their own UIWindow above
modal view controllers — Compose Multiplatform since 1.11 — end up with
the camera presented underneath that dialog window, which corrupts touch
handling app-wide after the picker dismissal (#638).

The camera presentation is now hosted in a FileKit-managed transparent
UIWindow made key above alerts, attached right before presenting and
detached — restoring the previous key window — once the capture flow
finishes, including failure paths. Apps passing an explicit presenter
through FileKitOpenCameraSettings keep the previous behavior.

Author: PierreVieira

filekit-dialogs/src/iosMain/kotlin/io/github/vinceglb/filekit/dialogs/FileKit.ios.kt

@@ -7,6 +7,7 @@ import io.github.vinceglb.filekit.dialogs.FileKitDialog.documentPickerDelegate
 import io.github.vinceglb.filekit.dialogs.FileKitDialog.phPickerDelegate
 import io.github.vinceglb.filekit.dialogs.FileKitDialog.phPickerDismissDelegate
 import io.github.vinceglb.filekit.dialogs.util.CameraControllerDelegate
+import io.github.vinceglb.filekit.dialogs.util.CameraPresenterWindow
 import io.github.vinceglb.filekit.dialogs.util.DocumentPickerDelegate
 import io.github.vinceglb.filekit.dialogs.util.PhPickerDelegate
 import io.github.vinceglb.filekit.dialogs.util.PhPickerDismissDelegate
@@ -287,37 +288,45 @@ public actual suspend fun FileKit.openCameraPicker(
                 null
             }
         }
-        val presentation = prepareAppleCameraPresentation(
-            sourceAvailable = UIImagePickerController.isSourceTypeAvailable(cameraSource),
-            presenter = openCameraSettings.presenterViewController(),
-            requestedCamera = requestedCamera,
-        )
-
-        suspendCancellableCoroutine<UIImage?> { continuation ->
-            cameraControllerDelegate = CameraControllerDelegate(
-                onImagePicked = { image ->
-                    try {
-                        continuation.resume(
-                            requireAppleCameraImage(image),
-                        )
-                    } catch (failure: FileKitDialogException) {
-                        continuation.resumeWithException(failure)
-                    }
-                },
-                onPickerCancelled = { continuation.resume(null) },
+        val presenterWindow = when (openCameraSettings.presenter) {
+            null -> CameraPresenterWindow()
+            else -> null
+        }
+        try {
+            val presentation = prepareAppleCameraPresentation(
+                sourceAvailable = UIImagePickerController.isSourceTypeAvailable(cameraSource),
+                presenter = openCameraSettings.presenter ?: presenterWindow?.attach(),
+                requestedCamera = requestedCamera,
             )
 
-            val pickerController = UIImagePickerController()
-            pickerController.sourceType = cameraSource
-            pickerController.delegate = cameraControllerDelegate
+            suspendCancellableCoroutine<UIImage?> { continuation ->
+                cameraControllerDelegate = CameraControllerDelegate(
+                    onImagePicked = { image ->
+                        try {
+                            continuation.resume(
+                                requireAppleCameraImage(image),
+                            )
+                        } catch (failure: FileKitDialogException) {
+                            continuation.resumeWithException(failure)
+                        }
+                    },
+                    onPickerCancelled = { continuation.resume(null) },
+                )
 
-            presentation.cameraDevice?.let { pickerController.cameraDevice = it }
+                val pickerController = UIImagePickerController()
+                pickerController.sourceType = cameraSource
+                pickerController.delegate = cameraControllerDelegate
 
-            presentation.presenter.presentViewController(
-                pickerController,
-                animated = true,
-                completion = null,
-            )
+                presentation.cameraDevice?.let { pickerController.cameraDevice = it }
+
+                presentation.presenter.presentViewController(
+                    pickerController,
+                    animated = true,
+                    completion = null,
+                )
+            }
+        } finally {
+            presenterWindow?.detach()
         }
     } ?: return null
 
@@ -525,9 +534,6 @@ private fun FileKitDialogSettings.presenterViewController(
     activeViewController: () -> UIViewController? = ::activeAppleViewController,
 ): UIViewController? = presenter ?: activeViewController()
 
-private fun FileKitOpenCameraSettings.presenterViewController(): UIViewController? =
-    presenter ?: UIApplication.sharedApplication.topMostViewController()
-
 private fun FileKitShareSettings.presenterViewController(): UIViewController? =
     presenter ?: UIApplication.sharedApplication.topMostViewController()
 

filekit-dialogs/src/iosMain/kotlin/io/github/vinceglb/filekit/dialogs/FileKitOpenCameraSettings.ios.kt

@@ -5,7 +5,10 @@ import platform.UIKit.UIViewController
 /**
  * iOS implementation of [FileKitOpenCameraSettings].
  *
- * @property presenter The view controller used to present the camera picker.
+ * @property presenter The view controller used to present the camera picker. When null, FileKit
+ * presents the camera from a dedicated window placed above the app's windows, which keeps the
+ * picker compatible with hosts whose dialogs live in their own window, such as Compose
+ * Multiplatform 1.11+.
  */
 public actual class FileKitOpenCameraSettings(
     public val presenter: UIViewController? = null,

filekit-dialogs/src/iosMain/kotlin/io/github/vinceglb/filekit/dialogs/util/CameraPresenterWindow.kt

@@ -0,0 +1,50 @@
+package io.github.vinceglb.filekit.dialogs.util
+
+import kotlinx.cinterop.ExperimentalForeignApi
+import platform.UIKit.UIApplication
+import platform.UIKit.UIColor
+import platform.UIKit.UIScreen
+import platform.UIKit.UIViewController
+import platform.UIKit.UIWindow
+import platform.UIKit.UIWindowLevelAlert
+import platform.UIKit.UIWindowScene
+
+/**
+ * Hosts the camera presentation in a dedicated transparent [UIWindow].
+ *
+ * Since Compose Multiplatform 1.11, Compose dialogs and popups live in their own window placed
+ * above modally presented view controllers. Presenting the fullscreen camera from the top-most
+ * view controller of the main window puts it underneath such windows, which corrupts touch
+ * handling app-wide after the dismissal. Presenting from a dedicated key window above alerts
+ * avoids that; the previous key window is restored once the capture flow finishes.
+ */
+internal class CameraPresenterWindow {
+    private val hostViewController = UIViewController()
+    private var window: UIWindow? = null
+    private var previousKeyWindow: UIWindow? = null
+
+    @OptIn(ExperimentalForeignApi::class)
+    fun attach(): UIViewController {
+        val application = UIApplication.sharedApplication
+        previousKeyWindow = application.keyWindow
+        val scene = application.connectedScenes.firstNotNullOfOrNull { it as? UIWindowScene }
+        val newWindow = when (scene) {
+            null -> UIWindow(frame = UIScreen.mainScreen.bounds)
+            else -> UIWindow(windowScene = scene)
+        }
+        newWindow.rootViewController = hostViewController
+        newWindow.windowLevel = UIWindowLevelAlert + 1.0
+        newWindow.backgroundColor = UIColor.clearColor
+        newWindow.makeKeyAndVisible()
+        window = newWindow
+        return hostViewController
+    }
+
+    fun detach() {
+        window?.setHidden(true)
+        window?.rootViewController = null
+        window = null
+        previousKeyWindow?.makeKeyAndVisible()
+        previousKeyWindow = null
+    }
+}