[Bug] iOS 13.5 - page content sometimes stops scrolling

[MitchBomcanhao]

Description

Have received a complaint from a user that SOMETIMES a page will stop scrolling.
This user did not have this issue until updating to iOS 13.5
I've updated a test device to the same version and managed to get this issue once so far, but no real reproduction steps yet.
The issue will surface while interacting with the page, ie it appears to load ok but then might stop scrolling altogether.

Has anyone seen or heard of similar issues?

It is a relatively basic page with a Grid > Scrollview > Stacklayout with a bunch of items that use AndreiMisiukevich's TouchEffect (4.0.21)
Those items will continue reacting to touch and everything else in the page will still work, except the scrolling.

Basic Information

• Version with issue: 4.2.0.910310
• Last known good version: n/a
• Platform Target Frameworks:
  • iOS: app compiled for ios 12

[MitchBomcanhao]

@AndreiMisiukevich Have you ever seen anything like this? perhaps the toucheffect component not releasing some events to the underlying scrollview?

[AndreiMisiukevich]

@AndreiMisiukevich Have you ever seen anything like this? perhaps the toucheffect component not releasing some events to the underlying scrollview?

Hi, I think the best ideas is checking it without TouchEffect

[AndreiMisiukevich]

frankly speaking, I don't see anything "scroll blocking"

https://github.com/AndreiMisiukevich/TouchEffect/blob/master/TouchEffect.iOS/PlatformTouchEff.cs

[MitchBomcanhao]

Hi, I think the best ideas is checking it without TouchEffect

I'm not having much luck in reproducing the issue at all - only happened once for me, so tinkering with the code is a bit pointless :( Your opinion is always welcome, even if only to eliminate TouchEffect as a suspect.

[AndreiMisiukevich]

Hi, I think the best ideas is checking it without TouchEffect

I'm not having much luck in reproducing the issue at all - only happened once for me, so tinkering with the code is a bit pointless :( Your opinion is always welcome, even if only to eliminate TouchEffect as a suspect.

Could you please share a sample project? (xaml markup)

[MitchBomcanhao]

Have something similar to this on a ContentPage.
This is not exactly how it is built in the actual app, but the structure is approximated. Added a few repeated items to force the app to have to scroll on this screen.

    <ContentPage.Resources>
        <ResourceDictionary>
            <Style x:Key="TouchEffectView" TargetType="ContentView">
                <Setter Property="touch:TouchEff.PressedAnimationDuration" Value="300" />
                <Setter Property="touch:TouchEff.PressedBackgroundColor" Value="Red" />
                <Setter Property="touch:TouchEff.RegularAnimationDuration" Value="200" />
                <Setter Property="touch:TouchEff.RippleCount" Value="1" />
            </Style>

            <ControlTemplate x:Key="ItemTemplate">
                <Grid>
                    <Grid Padding="15,30" RowSpacing="0" BackgroundColor="#DDDDDD">
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="Auto" />
                            <ColumnDefinition Width="*" />
                        </Grid.ColumnDefinitions>
                        <CheckBox Grid.Column="0" Margin="0" VerticalOptions="Center" IsChecked="True" Visual="Material"/>
                        <StackLayout Grid.Column="1" Spacing="0" VerticalOptions="Center">
                            <Label FontSize="Large" Text="Label" />
                            <Label FontSize="Small" Text="Another label"/>
                        </StackLayout>
                    </Grid>
                    <ContentView Style="{StaticResource TouchEffectView}" BackgroundColor="Green">
                        <ContentView.Effects>
                            <touch:TouchEff Completed="TouchView_Completed" />
                        </ContentView.Effects>
                    </ContentView>
                </Grid>
            </ControlTemplate>
        </ResourceDictionary>
    </ContentPage.Resources>

    <Grid RowSpacing="0">
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>

        <ScrollView Grid.Row="0">
            <StackLayout Spacing="0">
                <StackLayout Padding="15">
                    <Button HorizontalOptions="End" Visual="Material" Text="Some button" />
                    <Label Text="Label 1" />
                    <Label Text="Label 2" />
                </StackLayout>

                <StackLayout HorizontalOptions="Fill" Spacing="0" VerticalOptions="Fill">
                    <Button HorizontalOptions="End" Visual="Material" Text="Another button"/>
                    <StackLayout Spacing="5" Margin="0,0,0,150">
                        <ContentView ControlTemplate="{StaticResource ItemTemplate}"/>
                        <ContentView ControlTemplate="{StaticResource ItemTemplate}"/>
                        <ContentView ControlTemplate="{StaticResource ItemTemplate}"/>
                        <ContentView ControlTemplate="{StaticResource ItemTemplate}"/>
                        <ContentView ControlTemplate="{StaticResource ItemTemplate}"/>
                        <ContentView ControlTemplate="{StaticResource ItemTemplate}"/>
                        <ContentView ControlTemplate="{StaticResource ItemTemplate}"/>
                    </StackLayout>
                </StackLayout>
            </StackLayout>
        </ScrollView>
        <StackLayout Grid.Row="1" Padding="15">
            <Button Visual="Material" Text="OK" />
        </StackLayout>
    </Grid>

[samhouts]

@MitchBomcanhao Any chance you could put that into a sample project for us to test? Thanks!

[jsuarezruiz]

Tried to replicate but have not managed to get it. @MitchBomcanhao could you attach a reproduction sample?

[MitchBomcanhao]

I've not been able to reproduce this and have not had more time to chase it :( I still only have 1 user report and the one time I got it myself.
If this was a general issue I'd expect more reports as iOS 13.5 widened its distribution (we also increased our iOS user base), and probably also other reports from other xamarin devs, but nothing much has happened.

[mikepotvin]

@MitchBomcanhao @jsuarezruiz I've been able to reproduce this issue. It seems to only occur if you have a TouchEffect inside a ScrollView on iOS and it has to be at least 1 page deep in a navigation stack. For example there has to be the swipe to go back gesture enabled as well.

I've attached a sample repo with a sample video of it occuring
ScrollViewBreak.zip

scrollviewbreak.mp4