Hi @helang1991, can you post a reproduction of the issue as well as the output of flutter doctor? We will need more information to help you resolve it.

Hi @Piinks ,I clicked screen in other viewController by plugin, why the FlutterViewController received gesture events? Maybe other developers made similar issue.

Hi @helang1991, can you post a reproduction of the issue as well as the output of flutter doctor? We will need more information to help you resolve it.

I also met the problem, from the beginning, I want to develop a customized camera, a new plugin is developed to achieve this, the customized camera is a native page, when I open the camera page from flutter button, then there are two pages in app, foreground native camera page and background flutter page, something bad happened here were that when I click on the native camera page, the background futter page can receive the click event, eg. some button can react to these events.

Til now, I found the issue can be reproduced only in ios platform, android works well.

I found that image_picker have the same issue, please refer this link below:
#32896

Further more, to find the root cause, I replace the camera native page with one common native page of ios, this issue can be produced too

Any update on this issue? @Piinks Piinks

I encountered the same problem. Here is my investigation and current workaround.

Sample application

https://github.com/maeharin/flutter_ios_present_sample

Screenshot

Why this occured

Looking at the implementation of FlutterViewController (ex: engine v1.5.4-hotfixes branch), we can see they are overriding 4 methods(such as the touchesBegan). From here, the iOS touch event is propagated to the Flutter side
https://github.com/flutter/engine/blob/v1.5.4-hotfixes/shell/platform/darwin/ios/framework/Source/FlutterViewController.mm#L649-L663

See the apple documentation below for how to call touchesBegan. Touch events on the iOS side are designed to run up the Responder Chain
https://developer.apple.com/documentation/uikit/touches_presses_and_gestures/using_responders_and_the_responder_chain_to_handle_events

In our case, Responder Chain is like this

• Tap the part of UI where there is no event handler
• A tap event runs up the Responder Chain on iOS and propagates to FlutterViewController's touchesBegan ()
• Flutter side event handler is called

Workaround

The following workarounds can be considered

1. Override 4 methods of UIViewController that is presented from FlutterViewController

This prevents propagating unhandled events to FlutterViewController

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {}
override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {}

2. Stop doing present from FlutterViewController

Do not present() the UIViewController directly from the FlutterViewController, for example, by making the iOS side rootViewController a NavigationController instead of a FlutterViewController.
This article will be helpful for how to change rootViewController

https://medium.com/@najeira/change-ios-rootviewcontroller-with-flutter-fc4234f37105

I encountered the same problem. Here is my investigation and current workaround.

Sample application

https://github.com/maeharin/flutter_ios_present_sample

Screenshot

Why this occured

Looking at the implementation of FlutterViewController (ex: engine v1.5.4-hotfixes branch), we can see they are overriding 4 methods(such as the touchesBegan). From here, the iOS touch event is propagated to the Flutter side
https://github.com/flutter/engine/blob/v1.5.4-hotfixes/shell/platform/darwin/ios/framework/Source/FlutterViewController.mm#L649-L663

See the apple documentation below for how to call touchesBegan. Touch events on the iOS side are designed to run up the Responder Chain
https://developer.apple.com/documentation/uikit/touches_presses_and_gestures/using_responders_and_the_responder_chain_to_handle_events

In our case, Responder Chain is like this

• Tap the part of UI where there is no event handler
• A tap event runs up the Responder Chain on iOS and propagates to FlutterViewController's touchesBegan ()
• Flutter side event handler is called

Workaround

The following workarounds can be considered

1. Override 4 methods of UIViewController that is presented from FlutterViewController

This prevents propagating unhandled events to FlutterViewController

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {}
override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {}

2. Stop doing present from FlutterViewController

Do not present() the UIViewController directly from the FlutterViewController, for example, by making the iOS side rootViewController a NavigationController instead of a FlutterViewController.
This article will be helpful for how to change rootViewController

https://medium.com/@najeira/change-ios-rootviewcontroller-with-flutter-fc4234f37105

Thanks for your advice, I'll try your methods to fix it

Hi @helang1991
if the issue persist with the latest stable version of flutter
could you please provide your updated flutter doctor -v ,
your flutter run --verbose
and if possible a reproducible minimal code sample.
Thank you

Without additional information we are unfortunately not sure how to resolve this issue.
We are therefore reluctantly going to close this bug for now.
Please don't hesitate to comment on the bug if you have any more information for us; we will reopen it right away!
Thanks for your contribution.

Could everyone who still has this problem please file a new issue with the exact description of what happens, logs and the output of flutter doctor -v.
All system setups can be slightly different, so it's always better to open new issues and reference related issues.

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.