如何在xamarin表单中将FreshTabbedNavigationContainer选项卡页更改为顶部，以及更改ios的图标和字体大小

// 自定义渲染器类（Android）
[assembly: ExportRenderer(typeof(FreshTabbedNavigationContainer), typeof(CustomTabbedPageRenderer))]
namespace YourNamespace.Droid
{
    public class CustomTabbedPageRenderer : TabbedPageRenderer
    {
        protected override void OnElementChanged(ElementChangedEventArgs<TabbedPage> e)
        {
            base.OnElementChanged(e);

            if (e.NewElement != null)
            {
                // 将选项卡页放置在顶部
                var layout = (TabLayout)ViewGroup.GetChildAt(1);
                layout.Gravity = GravityFlags.Top;
            }
        }
    }
}

// 自定义渲染器类（iOS）
[assembly: ExportRenderer(typeof(FreshTabbedNavigationContainer), typeof(CustomTabbedRenderer))]
namespace YourNamespace.iOS
{
    public class CustomTabbedRenderer : TabbedRenderer
    {
        public override void ViewWillAppear(bool animated)
        {
            base.ViewWillAppear(animated);

            if (TabBar != null)
            {
                // 将选项卡页放置在顶部
                TabBar.Translucent = false;
                TabBar.BarPosition = UIBarPosition.Top;

                // 设置选项卡标题的字体大小和样式
                var attributes = new UITextAttributes
                {
                    Font = UIFont.SystemFontOfSize(12) // 设置字体大小
                    // 其他样式设置
                };

                UITabBarItem.Appearance.SetTitleTextAttributes(attributes, UIControlState.Normal);
                UITabBarItem.Appearance.SetTitleTextAttributes(attributes, UIControlState.Selected);

                // 调整选项卡标题的位置
                foreach (var item in TabBar.Items)
                {
                    item.TitlePositionAdjustment = new UIOffset(0, -10); // 调整位置
                }
            }
        }
    }
}