Navigating to Screen which is not wrapped by Scaffold causes laggy on iOS

[mthinh]

Steps to Reproduce

1. Screen A navigate to Screen B
2. Screen B returns a widget without being wrapped by Scaffold widget (ex CircularProgressIndicator)

Expected results:

Navigating should be smooth

Actual results:

It's laggy here

Code sample

class ScreenA extends StatelessWidget {
  const ScreenA({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(floatingActionButton: FloatingActionButton(
      onPressed: () {
        Navigator.push(
            context, MaterialPageRoute(builder: (context) => const ScreenB()));
      },
    ));
  }
}


class ScreenB extends StatelessWidget {
  const B({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const Center(child: CircularProgressIndicator());
  }
}

Logs

Doctor summary (to see all details,
run flutter doctor -v):
[✓] Flutter (Channel stable, 2.8.1, on
    macOS 12.0.1 21A559 darwin-x64,
    locale en-US)
[✓] Android toolchain - develop for
    Android devices (Android SDK
    version 32.0.0)
[✓] Xcode - develop for iOS and macOS
    (Xcode 13.2.1)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2020.3)
[✓] VS Code (version 1.63.2)
[✓] Connected device (2 available)

• No issues found!

[darshankawar]

Thanks for the report. I do see the same behavior using latest master and stable. If screen B doesn't have Scaffold widget, then the routing seems to a bit lagged / slow and also while swiping back, the transition isn't smooth as shown below:

97109.mov

After adding Scaffold on screen B and giving it a background color to match the same scenario, the routing is smooth and swiping back gesture is also proper and as expected, as shown below:

97109_1.mov

master, stable flutter doctor -v

[✓] Flutter (Channel master, 2.9.0-1.0.pre.463, on Mac OS X 10.15.4 19E2269
    darwin-x64, locale en-GB)
    • Flutter version 2.9.0-1.0.pre.463 at
      /Users/dhs/documents/fluttersdk/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision e92d8ef2b1 (13 hours ago), 2022-01-23 13:20:17 -0500
    • Engine revision 4f58a01268
    • Dart version 2.17.0 (build 2.17.0-48.0.dev)
    • DevTools version 2.9.2

[!] Xcode - develop for iOS and macOS (Xcode 12.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    ! Flutter recommends a minimum Xcode version of 13.
      Download the latest version or update via the Mac App Store.
    • CocoaPods version 1.11.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] VS Code (version 1.62.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.21.0

[✓] Connected device (4 available)
    • Darshan's iphone (mobile)  • 21150b119064aecc249dfcfe05e259197461ce23 •
      ios            • iOS 14.4.1 18D61
    • iPhone 12 Pro Max (mobile) • A5473606-0213-4FD8-BA16-553433949729     •
      ios            • com.apple.CoreSimulator.SimRuntime.iOS-14-3 (simulator)
    • macOS (desktop)            • macos                                    •
      darwin-x64     • Mac OS X 10.15.4 19E2269 darwin-x64
    • Chrome (web)               • chrome                                   •
      web-javascript • Google Chrome 97.0.4692.71

[✓] HTTP Host Availability
    • All required HTTP hosts are available

! Doctor found issues in 1 category.

[✓] Flutter (Channel stable, 2.8.1, on Mac OS X 10.15.4 19E2269 darwin-x64,
    locale en-GB)
    • Flutter version 2.8.1 at /Users/dhs/documents/fluttersdk/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 77d935af4d (13 hours ago), 2021-12-16 08:37:33 -0800
    • Engine revision 890a5fca2e
    • Dart version 2.15.1

[✓] Android toolchain - develop for Android devices (Android SDK version 30)
    • Android SDK at /Users/dhs/Library/Android/sdk
    • Platform android-30, build-tools 30.0.3
    • ANDROID_HOME = /Users/dhs/Library/Android/sdk
    • Java binary at: /Users/dhs/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/202.7486908/Android
      Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
    • All Android licenses accepted.    

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 12.3, Build version 12C33
    • CocoaPods version 1.10.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 4.1)
    • Android Studio at /Users/dhs/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/202.7486908/Android
      Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build
      1.8.0_242-release-1644-b3-6915495)        

[✓] VS Code (version 1.57.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.21.0

[✓] Connected device (4 available)
    • Darshan's iphone (mobile)  • 21150b119064aecc249dfcfe05e259197461ce23 •
      ios            • iOS 14.4.1 18D61
    • iPhone 12 Pro Max (mobile) • A5473606-0213-4FD8-BA16-553433949729     •
      ios            • com.apple.CoreSimulator.SimRuntime.iOS-14-3 (simulator)
    • macOS (desktop)            • macos                                    •
      darwin-x64     • Mac OS X 10.15.4 19E2269 darwin-x64
    • Chrome (web)               • chrome                                   •
      web-javascript • Google Chrome 93.0.4577.82


• No issues found!

[netDinger]

Is this problem still persist? I am still facing the same problem.