Xamarin forms iOS，如何自定义导航栏？

public class CustomNavigationPage : Xamarin.Forms.NavigationPage
{
    public CustomNavigationPage(Page root) : base(root)
    {
        // 在构造函数中设置导航栏的样式
        BarBackgroundColor = Color.Blue;
        BarTextColor = Color.White;
    }
}

MainPage = new CustomNavigationPage(new MainPage());

NavigationPage.SetTitleView(this, new CustomTitleView()); // 设置自定义标题视图
NavigationPage.SetHasNavigationBar(this, false); // 隐藏导航栏

public class CustomTitleView : Xamarin.Forms.View
{
    public CustomTitleView()
    {
        // 在构造函数中添加自定义的控件
        var titleLabel = new Label
        {
            Text = "Custom Title",
            TextColor = Color.White,
            HorizontalOptions = LayoutOptions.CenterAndExpand,
            VerticalOptions = LayoutOptions.CenterAndExpand
        };

        var backButton = new Button
        {
            Text = "Back",
            TextColor = Color.White,
            BackgroundColor = Color.Transparent,
            HorizontalOptions = LayoutOptions.Start,
            VerticalOptions = LayoutOptions.CenterAndExpand
        };
        backButton.Clicked += (sender, e) =>
        {
            // 处理返回按钮的点击事件
            Navigation.PopAsync();
        };

        // 将控件添加到自定义标题视图中
        var titleLayout = new StackLayout
        {
            Orientation = StackOrientation.Horizontal,
            Children = { backButton, titleLabel }
        };
        Content = titleLayout;
    }
}