[image_picker] Transparent pressing on iOS 26 (#173453)

Issue: On iOS, taps on the camera confirmation bar (“Use Photo” / “Retake”) were leaking through UIImagePickerController and dismissing underlying UI (e.g., bottom sheets) — a system touch-through regression reported on iOS 26 and some 18.x devices.

What I changed: In ios/image_picker_ios/Sources/image_picker_ios/FLTImagePickerPlugin.m, before presenting the camera picker I now create a transparent, high-level UIWindow to absorb touches and restore the previous key window once the picker finishes or is cancelled.

This aims to block those leaked taps without changing Flutter-side UX.

Author: Calvin Ren

packages/image_picker/image_picker_ios/example/lib/main.dart

@@ -522,7 +522,9 @@ class _MyHomePageState extends State<MyHomePage> {
                     ? int.parse(limitController.text)
                     : null;
                 onPick(width, height, quality, limit);
-                Navigator.of(context).pop();
+                // Leave the dialog open to verify that tapping the transparent area no longer pops it.
+                // Regression check for https://github.com/flutter/flutter/issues/173453.
+                // Navigator.of(context).pop();
               },
             ),
           ],

packages/image_picker/image_picker_ios/ios/image_picker_ios/Sources/image_picker_ios/FLTImagePickerPlugin.m

@@ -37,6 +37,8 @@ @interface FLTImagePickerPlugin ()
 /// the array.
 @property(strong, nonatomic)
     NSMutableArray<UIImagePickerController *> *imagePickerControllerOverrides;
+@property(strong, nonatomic) UIWindow *interactionBlockerWindow;
+@property(weak, nonatomic) UIWindow *previousKeyWindow;
 
 @end
 
@@ -322,6 +324,7 @@ - (void)showCamera:(UIImagePickerControllerCameraDevice)device
       [UIImagePickerController isCameraDeviceAvailable:device]) {
     imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;
     imagePickerController.cameraDevice = device;
+    [self addInteractionBlocker];
     [[self viewControllerWithWindow:nil] presentViewController:imagePickerController
                                                       animated:YES
                                                     completion:nil];
@@ -531,7 +534,10 @@ - (void)picker:(PHPickerViewController *)picker
 - (void)imagePickerController:(UIImagePickerController *)picker
     didFinishPickingMediaWithInfo:(NSDictionary<NSString *, id> *)info {
   NSURL *videoURL = info[UIImagePickerControllerMediaURL];
-  [picker dismissViewControllerAnimated:YES completion:nil];
+  [picker dismissViewControllerAnimated:YES
+                             completion:^{
+                               [self removeInteractionBlocker];
+                             }];
   // The method dismissViewControllerAnimated does not immediately prevent
   // further didFinishPickingMediaWithInfo invocations. A nil check is necessary
   // to prevent below code to be unwantly executed multiple times and cause a
@@ -617,7 +623,10 @@ - (void)imagePickerController:(UIImagePickerController *)picker
 }
 
 - (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
-  [picker dismissViewControllerAnimated:YES completion:nil];
+  [picker dismissViewControllerAnimated:YES
+                             completion:^{
+                               [self removeInteractionBlocker];
+                             }];
   [self sendCallResultWithSavedPathList:nil];
 }
 
@@ -673,4 +682,40 @@ - (void)sendCallResultWithError:(FlutterError *)error {
   self.callContext = nil;
 }
 
+- (void)addInteractionBlocker {
+  if (self.interactionBlockerWindow != nil) {
+    return;
+  }
+  UIViewController *topController = [self viewControllerWithWindow:nil];
+  UIWindow *presentingWindow = topController.view.window;
+  if (!presentingWindow) {
+    return;
+  }
+  self.previousKeyWindow = presentingWindow;
+  UIWindow *blockerWindow;
+  if (@available(iOS 13.0, *)) {
+    blockerWindow = [[UIWindow alloc] initWithWindowScene:presentingWindow.windowScene];
+  } else {
+    blockerWindow = [[UIWindow alloc] initWithFrame:presentingWindow.bounds];
+  }
+  blockerWindow.frame = presentingWindow.bounds;
+  blockerWindow.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
+  blockerWindow.windowLevel = presentingWindow.windowLevel + 1;
+  UIViewController *vc = [[UIViewController alloc] init];
+  vc.view.backgroundColor = [UIColor clearColor];
+  vc.view.userInteractionEnabled = YES;
+  blockerWindow.rootViewController = vc;
+  [blockerWindow makeKeyAndVisible];
+  self.interactionBlockerWindow = blockerWindow;
+}
+
+- (void)removeInteractionBlocker {
+  self.interactionBlockerWindow.hidden = YES;
+  if (self.previousKeyWindow) {
+    [self.previousKeyWindow makeKeyWindow];
+  }
+  self.interactionBlockerWindow = nil;
+  self.previousKeyWindow = nil;
+}
+
 @end