[Bug] iOS Setting FlyoutItem IsVisible to false blocks loading of modal views

[bnoffer]

Description

After upgrading to Xamarin.Forms 5 we encountered a strange issue: We have a use case in our app where we want to hide a FlyoutItem on demand therefore the IsVisible property is bound to a ViewModel property. When setting the property to false it now blocks all modal pages pushed via Shell.Current.Navigation.PushModalAsync() from being displayed. You can see that the page is loaded, but it is never shown on screen. Making the FlyoutItem visible again returns everything to normal operation. This occurs only on iOS.

Steps to Reproduce

See description above.

Expected Behavior

Modal views should be visible even if a FlyoutItem is set to be not visible.

Actual Behavior

Modal views are not visible when a FlyoutItem is set to not visible.

Basic Information

• Version with issue: 5.0.0.2012 and above
• Last known good version: 4.8.0.1821
• Platform Target Frameworks:
  • iOS: 15.2
• NuGet Packages:
• Affected Devices: iPhones

Environment

Show/Hide Visual Studio info

Visual Studio Community 2019 for Mac
Version 8.10.17 (build 2)
Installation UUID: eb5dba2d-bed2-49ed-af10-410cb4cd09f4
GTK+ 2.24.23 (Raleigh theme)
Xamarin.Mac 6.18.0.23 (d16-6 / 088c73638)

Package version: 612000162

Mono Framework MDK
Runtime:
Mono 6.12.0.162 (2020-02/2ca650f1f62) (64-bit)
Package version: 612000162

Roslyn (Language Service)
3.10.0-4.21269.26+029847714208ebe49668667c60ea5b0a294e0fcb

NuGet
Version: 5.9.0.7134

.NET SDK (x64)
SDK: /usr/local/share/dotnet/sdk/6.0.101/Sdks
SDK Versions:
6.0.101
6.0.100
6.0.100-rc.1.21463.6
5.0.404
5.0.403
5.0.402
5.0.401
5.0.400
5.0.302
5.0.301
5.0.203
3.1.416
3.1.415
3.1.414
3.1.413
3.1.412
3.1.411
3.1.410
3.1.409
MSBuild SDKs: /Applications/Visual Studio.app/Contents/Resources/lib/monodevelop/bin/MSBuild/Current/bin/Sdks

.NET Core Runtime
Runtime: /usr/local/share/dotnet/dotnet
Runtime Versions:
6.0.1
6.0.0
6.0.0-rc.1.21451.13
5.0.13
5.0.12
5.0.11
5.0.10
5.0.9
5.0.8
5.0.7
5.0.6
3.1.22
3.1.21
3.1.20
3.1.19
3.1.18
3.1.17
3.1.16
3.1.15

Xamarin.Profiler
Version: 1.7.0.0
Location: /Applications/Xamarin Profiler.app/Contents/MacOS/Xamarin Profiler

Updater
Version: 11

Xamarin Designer
Version: 16.11.0.60
Hash: 56f9b80b0
Branch: remotes/origin/d16-11
Build date: 2021-12-15 02:44:16 UTC

Apple Developer Tools
Xcode 13.2.1 (19586)
Build 13C100

Xamarin.Mac
Version: 8.4.0.0 (Visual Studio Community)
Hash: 8fc41ae82
Branch: xcode13.2
Build date: 2021-12-09 01:07:56-0500

Xamarin.iOS
Version: 15.4.0.0 (Visual Studio Community)
Hash: 8fc41ae82
Branch: xcode13.2
Build date: 2021-12-09 01:07:56-0500

Xamarin.Android
Version: 12.0.0.3 (Visual Studio Community)
Commit: xamarin-android/d16-11/f0e3c2d
Android SDK: /Users/bastian.noffer/Library/Developer/Xamarin/android-sdk-macosx
Supported Android versions:
None installed

SDK Tools Version: 26.1.1
SDK Platform Tools Version: 31.0.2
SDK Build Tools Version: 30.0.3

Build Information:
Mono: c633fe9
Java.Interop: xamarin/java.interop@476bb5b
ProGuard: Guardsquare/proguard@912d149
SQLite: xamarin/sqlite@85460d3
Xamarin.Android Tools: xamarin/xamarin-android-tools@87af37b

Eclipse Temurin JDK
Java SDK: Not Found

Android SDK Manager
Version: 16.10.0.13
Hash: 1b81df5
Branch: remotes/origin/d16-10
Build date: 2021-11-12 01:17:32 UTC

Android Device Manager
Version: 16.10.0.15
Hash: 89dcc0b
Branch: remotes/origin/d16-10
Build date: 2021-11-12 01:17:52 UTC

Build Information
Release ID: 810170002
Git revision: 58f7763d4d64fcf005a474d25a5d9fd5ce46d7f5
Build date: 2022-01-05 12:51:28-05
Build branch: release-8.10

Operating System
Mac OS X 11.6.2
Darwin 20.6.0 Darwin Kernel Version 20.6.0
Wed Nov 10 22:23:07 PST 2021
root:xnu-7195.141.14~1/RELEASE_X86_64 x86_64

Enabled user installed extensions
DeepClean 1.2.5
NuGet Package Management Extensions 0.27
Template Creator 0.5
Open With 0.2

Reproduction Link

Sample Project: https://github.com/bnoffer/xamarin-iussee-flyoutmodal
In order to to show the behavior manipulate the variable in this line: https://github.com/bnoffer/xamarin-iussee-flyoutmodal/blob/815ea33726258c2cb698c00718cb0115d3a1b4d4/FlyoutModalIssue/AppShellViewModel.cs#L26

[abosquet]

Same issue for me. Any plan to fix it in a soon release?

[anotherlab]

We had to implement an ugly workaround for this (disable instead and blank out the title & icon). Are there any plans on addressing this?

[deepikacis]

We had to implement an ugly workaround for this (disable instead and blank out the title & icon). Are there any plans on addressing this?

@anotherlab, have you found any workaround for this?

[zbulleit]

For anyone who is still having trouble with this, I found a potential workaround that might be suitable. Of course, if there is a more practical option, please share.

<Shell.FlyoutContent>
        <StackLayout BackgroundColor="White" Spacing="3" Padding="5">

            <Button x:Name="selectProject" Text="Select Project" ImageSource="{StaticResource project}" BackgroundColor="Transparent" HorizontalOptions="StartAndExpand" 
                    Command="{Binding FlyoutButtonTappedCommand}" CommandParameter="selectProject" />
            <Button x:Name="checklist" Text="Checklist" ImageSource="{StaticResource checklist}" BackgroundColor="Transparent" HorizontalOptions="StartAndExpand" 
                    Command="{Binding FlyoutButtonTappedCommand}" CommandParameter="checklist" />
            <Button x:Name="schedule" Text="Schedule" ImageSource="{StaticResource schedule}" BackgroundColor="Transparent" HorizontalOptions="StartAndExpand" 
                    Command="{Binding FlyoutButtonTappedCommand}" CommandParameter="schedule" />

        </StackLayout>
    </Shell.FlyoutContent>

Each button can easily be hidden and the PushModalAsync works as expected.

The command 'FlyoutButtonTappedCommand' is basically a switch statement that navigates the user to a page that is determined by the CommandParameter. After the switch statement is completed, the flyout is programmatically closed.