How do I implement CustomMoreNavigationControllerDelegate using ShellRenderer? - xamarin

Question

Previously I was able to use TabbedRenderer to stylize the tabbed bar More menu page by implementing CustomMoreNavigationControllerDelegate as so...
public class ExtendedTabbedPageRenderer : TabbedRenderer
{
protected override void OnElementChanged(VisualElementChangedEventArgs e)
{
base.OnElementChanged(e);
if (e.NewElement != null)
{
MoreNavigationController.Delegate = new CustomMoreNavigationControllerDelegate();
}
}
}
I'm now using Shell navigation instead, and so how can I assign/implement this class using ShellRenderer (since there is no OnElementChanged override)?
My More menu styling class
internal class CustomMoreNavigationControllerDelegate : UINavigationControllerDelegate
{
public override void WillShowViewController(UINavigationController navigationController, UIViewController viewController, bool animated)
{
viewController.NavigationController.NavigationBarHidden = false;
UILabel titleLabel = new UILabel();
if (viewController.NavigationItem.Title != "More")
{
titleLabel.Text = viewController.NavigationItem.Title;
}
else
{
titleLabel.Text = "More";
}
titleLabel.TextColor = Xamarin.Forms.Application.Current.UserAppTheme == OSAppTheme.Dark ? UIColor.White : UIColor.Black;
viewController.NavigationItem.TitleView = titleLabel;
viewController.View.BackgroundColor = Xamarin.Forms.Application.Current.UserAppTheme == OSAppTheme.Dark ? ExtendedTabbedPageRenderer.iOSDarkPageBackgroundColor : ExtendedTabbedPageRenderer.iOSLightPageBackgroundColor;
viewController.View.TintColor = Xamarin.Forms.Application.Current.UserAppTheme == OSAppTheme.Dark ? UIColor.White : UIColor.Black;
if (viewController.View is UITableView tableView)
{
tableView.SeparatorColor = Xamarin.Forms.Application.Current.UserAppTheme == OSAppTheme.Dark ? UIColor.White : UIColor.Black;
foreach (var cell in tableView.VisibleCells)
{
cell.BackgroundColor = Xamarin.Forms.Application.Current.UserAppTheme == OSAppTheme.Dark ? ExtendedTabbedPageRenderer.iOSDarkPageBackgroundColor : ExtendedTabbedPageRenderer.iOSLightPageBackgroundColor;
cell.TextLabel.TextColor = cell.TintColor = Xamarin.Forms.Application.Current.UserAppTheme == OSAppTheme.Dark ? UIColor.White : UIColor.Black;
}
}
}
}

Answer 1

You need override the required methods to perform the required customization via a subclass of the ShellRenderer class to customize the Tabbar appearance.
For example,in iOS, if you want to set the text of the more menu of the Shell application.
Code snippet:
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;
[assembly: ExportRenderer(typeof(Xaminals.AppShell), typeof(Xaminals.iOS.MyShellRenderer))]
namespace Xaminals.iOS
{
public class MyShellRenderer : ShellRenderer
{
protected override IShellTabBarAppearanceTracker CreateTabBarAppearanceTracker()
{
return new TabBarAppearance();
}
}
public class TabBarAppearance : IShellTabBarAppearanceTracker
{
public void Dispose()
{
}
public void ResetAppearance(UITabBarController controller)
{
}
public void SetAppearance(UITabBarController controller, ShellAppearance appearance)
{
//set tabbar appearance
}
public void UpdateLayout(UITabBarController controller)
{
UITabBar tb = controller.MoreNavigationController.TabBarController.TabBar;
if (tb.Subviews.Length > 4)
{
UIView tbb = tb.Subviews[4];
UILabel label = (UILabel)tbb.Subviews[1];
label.Text = "CustomTab";
}
}
}
}
For more details, please refer to our MS official docs.