TabIndicator not showing when landing on page - iOS Only

[LeoJHarris]

Appears like a bug that when landing on a page with the TabView that the TabIndicatorColor is not showing initially, when I select another tab then the color changes. The color of the TabIndicatorColor is referenced as a DynamicResource in XAML.

Expected Behavior

Color of the TabIndicatorColor should show when page appeared

Actual Behavior

The TabIndicatorColor does not show when page appear and only shows when selecting a new tab then the TabIndicatorColor indicated the correct color for the selected tab

Basic Information

• Version with issue:
• Last known good version: NA
• IDE:VS community 2019
• Platform Target Frameworks:
  • iOS: iOS 14.4
  • Android: NA
  • UWP: NA
• Android Support Library Version: NA
• Nuget Packages: NA
• Affected Devices: Simulator and iphone

Workaround

NONE

Reproduction imagery

When page is first appeared the TabIndicatorColor is not shown:

When selecting the next tab it then shows:

Reproduction Link

[Kapusch]

I also have noticed this bug many times, but I cannot say why...

Actually, anytime I sign out / sign in again to my app, then I'm able to the the TabIndicatorColor once landing on page !

I guess it could be something related to events ordering, BindingContext initializations... I'll comment more in case I get it.

[Kapusch]

Hi @LeoJHarris ,

Did you try just setting "SelectedIndex" property with a default value ? SelectedIndex="0"

[LeoJHarris]

@Kapusch yes same issue occurs

[LeoJHarris]

@Kapusch If this is only occurring on iOS and not on android then how could events ordering, BindingContext initializations be factors are these handled differently on iOS?

[Mirksar]

I am also having this issue on my app.

I have noticed that this this bug is only happening when the TabView page is opened using Application.Current.MainPage.Navigation.PushAsync

When setting the page directly as Application.Current.MainPage the TabIndicatorColor is showing correctly.

[Kapusch]

Hi @LeoJHarris , I'm facing this issue once again, and I may have found a workaround. Could you try to set the SelectedIndex in the view "OnAppearing" event ? (not working if set in the view constructor)

Of course, this supposes to work on ContentPage views, I'm still trying to find a way to make it work for my ContentView views.

[LeoJHarris]

@Kapusch there is a better work around to set the TabIndicatorView yourself in XAML as shown below.

<xct:TabView>
        <xct:TabView.TabIndicatorView>
            <BoxView
                WidthRequest="{Binding Source={x:Reference tabItemBase}, Path=Width}" />
        </xct:TabView.TabIndicatorView>

        <xct:TabViewItem
            x:Name="tabItemBase"