[iOS] Shell doesn’t expose an easy way to enable large titles + translucent navbar

[paulober]

Description

Currently this is only possible with ios: for NavigationPages but not Shell Apps which require a custom solution. I thought my solution could be upstreamed and made available as little helper for shell apps.

public class CustomAppShell : ShellRenderer
{
    protected override IShellNavBarAppearanceTracker CreateNavBarAppearanceTracker()
    {
        return new LargeTitleNavBarAppearanceTracker();
    }
}

public class LargeTitleNavBarAppearanceTracker : IShellNavBarAppearanceTracker
{
    public void Dispose() { }

    public void ResetAppearance(UINavigationController controller) { }

    public void SetAppearance(UINavigationController controller, ShellAppearance appearance)
    {
        var navBar = controller.NavigationBar;

        // Big titles
        navBar.PrefersLargeTitles = true;

        // Translucent / no separator line
        var navBarAppearance = new UINavigationBarAppearance();
        navBarAppearance.ConfigureWithTransparentBackground();
        navBarAppearance.BackgroundColor = UIColor.Clear;
        navBarAppearance.ShadowColor = UIColor.Clear;   // remove bottom hairline
        navBarAppearance.BackgroundEffect = null;

        // Respect Shell colors if used
        if (appearance?.ForegroundColor is not null)
        {
            var fg = appearance.ForegroundColor;
            var uiFg = UIColor.FromRGBA((nfloat)fg.Red, (nfloat)fg.Green, (nfloat)fg.Blue, (nfloat)fg.Alpha);

            navBarAppearance.TitleTextAttributes = new UIStringAttributes { ForegroundColor = uiFg };
            navBarAppearance.LargeTitleTextAttributes = new UIStringAttributes { ForegroundColor = uiFg };
        }

        navBar.StandardAppearance = navBarAppearance;
        navBar.ScrollEdgeAppearance = navBarAppearance;

        // Force large titles on the current VC without touching ContentPages
        if (controller.TopViewController is { } vc)
            vc.NavigationItem.LargeTitleDisplayMode = UINavigationItemLargeTitleDisplayMode.Always;
    }

    public void UpdateLayout(UINavigationController controller) { }

    public void SetHasShadow(UINavigationController controller, bool hasShadow)
    {
        // we already removed shadow via ShadowColor = Clear
        // so ignore
    }
}

I will try to create a PR for this but feedback on how to best integrate this are very Wellcome.

Public API Changes

<Shell
  xmlns:ios="clr-namespace:Microsoft.Maui.Controls.PlatformConfiguration.iOSSpecific;assembly=Microsoft.Maui.Controls"
  ios:Shell.PrefersLargeTitles="true"
  ios:Shell.IsNavigationBarTranslucent="true">

Intended Use-Case

To create more native looking apps for iOS 26. Apple now uses this still in many of their current apps like the Sports app.

[kubaflo]

Hi @paulober! This will be fully covered in the next release 😊
PR: #32081
Thanks for raising the concern - appreciate the caution!

[kubaflo]

Duplicate of #12156