C# 如何更改Shell Tabbar高度

我的问题是： 我将Shell与底部

Tabbar

一起使用，我只想在Android上或者iOS上更改它的高度

我的搜索结果： 我知道，

Tabbar

是一个Android/iOS内置功能，具有固定的指定高度

似乎有一种方法可以使用“自定义渲染器”实现这一点。我发现的所有使用这种方法的项目都不能与我的VisualStudio一起工作（>100个错误或干脆什么都不做）

我发现很难相信我需要超过100行的代码来“仅”调整高度。是否有人能提供一个有效的解决方案来更改外壳选项卡（底部选项卡）的高度

编辑

---

毫无疑问，您需要在每个平台项目上创建自定义渲染器：

安卓

MyShellRenderer

class

[assembly: ExportRenderer(typeof(App.AppShell), typeof(App.Droid.MyShellRenderer))]

namespace App.Droid
{
    public class MyShellRenderer : ShellRenderer
    {
        public MyShellRenderer(Context context) : base(context)
        {
        }

    protected override IShellBottomNavViewAppearanceTracker CreateBottomNavViewAppearanceTracker(ShellItem shellItem)
        {
            return new MyBottomNavViewAppearanceTracker(this, shellItem);
        }
    }
}

class MyBottomNavViewAppearanceTracker : ShellBottomNavViewAppearanceTracker
    {
        public MyBottomNavViewAppearanceTracker(IShellContext shellContext, ShellItem shellItem) : base(shellContext, shellItem)
        {
        }
        public override void SetAppearance(BottomNavigationView bottomView, IShellAppearanceElement appearance)
        {
            bottomView.LayoutParameters.Height = 400;
            base.SetAppearance(bottomView, appearance);
        }
    }

[assembly: ExportRenderer(typeof(App.AppShell), typeof(App.iOS.MyShellRenderer))]

namespace App.iOS
{
    public class MyShellRenderer : ShellRenderer
    {

        protected override IShellTabBarAppearanceTracker CreateTabBarAppearanceTracker()
        {
            return new MyCreateTabBarAppearanceTracker();
        }
    }
}

class CreateTabBarAppearanceTracker : ShellTabBarAppearanceTracker
    {
    
        public override void SetAppearance(UITabBarController controller, ShellAppearance appearance)
        {
            UITabBar tabBar = controller.TabBar;
            int tabBarHeight = 100;

            if (tabBar.Frame.Height != tabBarHeight)
            {
                tabBar.Frame = new CGRect(tabBar.Frame.X, tabBar.Frame.Y + (tabBar.Frame.Height - tabBarHeight), tabBar.Frame.Width, tabBarHeight); 
            }
        }
    }

MyBottomNavViewAppearanceTracker

class

[assembly: ExportRenderer(typeof(App.AppShell), typeof(App.Droid.MyShellRenderer))]

namespace App.Droid
{
    public class MyShellRenderer : ShellRenderer
    {
        public MyShellRenderer(Context context) : base(context)
        {
        }

    protected override IShellBottomNavViewAppearanceTracker CreateBottomNavViewAppearanceTracker(ShellItem shellItem)
        {
            return new MyBottomNavViewAppearanceTracker(this, shellItem);
        }
    }
}

class MyBottomNavViewAppearanceTracker : ShellBottomNavViewAppearanceTracker
    {
        public MyBottomNavViewAppearanceTracker(IShellContext shellContext, ShellItem shellItem) : base(shellContext, shellItem)
        {
        }
        public override void SetAppearance(BottomNavigationView bottomView, IShellAppearanceElement appearance)
        {
            bottomView.LayoutParameters.Height = 400;
            base.SetAppearance(bottomView, appearance);
        }
    }

[assembly: ExportRenderer(typeof(App.AppShell), typeof(App.iOS.MyShellRenderer))]

namespace App.iOS
{
    public class MyShellRenderer : ShellRenderer
    {

        protected override IShellTabBarAppearanceTracker CreateTabBarAppearanceTracker()
        {
            return new MyCreateTabBarAppearanceTracker();
        }
    }
}

class CreateTabBarAppearanceTracker : ShellTabBarAppearanceTracker
    {
    
        public override void SetAppearance(UITabBarController controller, ShellAppearance appearance)
        {
            UITabBar tabBar = controller.TabBar;
            int tabBarHeight = 100;

            if (tabBar.Frame.Height != tabBarHeight)
            {
                tabBar.Frame = new CGRect(tabBar.Frame.X, tabBar.Frame.Y + (tabBar.Frame.Height - tabBarHeight), tabBar.Frame.Width, tabBarHeight); 
            }
        }
    }

编辑： iOS的一部分归功于

网间网操作系统

MyShellRenderer

class

[assembly: ExportRenderer(typeof(App.AppShell), typeof(App.Droid.MyShellRenderer))]

namespace App.Droid
{
    public class MyShellRenderer : ShellRenderer
    {
        public MyShellRenderer(Context context) : base(context)
        {
        }

    protected override IShellBottomNavViewAppearanceTracker CreateBottomNavViewAppearanceTracker(ShellItem shellItem)
        {
            return new MyBottomNavViewAppearanceTracker(this, shellItem);
        }
    }
}

class MyBottomNavViewAppearanceTracker : ShellBottomNavViewAppearanceTracker
    {
        public MyBottomNavViewAppearanceTracker(IShellContext shellContext, ShellItem shellItem) : base(shellContext, shellItem)
        {
        }
        public override void SetAppearance(BottomNavigationView bottomView, IShellAppearanceElement appearance)
        {
            bottomView.LayoutParameters.Height = 400;
            base.SetAppearance(bottomView, appearance);
        }
    }

[assembly: ExportRenderer(typeof(App.AppShell), typeof(App.iOS.MyShellRenderer))]

namespace App.iOS
{
    public class MyShellRenderer : ShellRenderer
    {

        protected override IShellTabBarAppearanceTracker CreateTabBarAppearanceTracker()
        {
            return new MyCreateTabBarAppearanceTracker();
        }
    }
}

class CreateTabBarAppearanceTracker : ShellTabBarAppearanceTracker
    {
    
        public override void SetAppearance(UITabBarController controller, ShellAppearance appearance)
        {
            UITabBar tabBar = controller.TabBar;
            int tabBarHeight = 100;

            if (tabBar.Frame.Height != tabBarHeight)
            {
                tabBar.Frame = new CGRect(tabBar.Frame.X, tabBar.Frame.Y + (tabBar.Frame.Height - tabBarHeight), tabBar.Frame.Width, tabBarHeight); 
            }
        }
    }

CreateTabBarAppearanceTracker

class

[assembly: ExportRenderer(typeof(App.AppShell), typeof(App.Droid.MyShellRenderer))]

namespace App.Droid
{
    public class MyShellRenderer : ShellRenderer
    {
        public MyShellRenderer(Context context) : base(context)
        {
        }

    protected override IShellBottomNavViewAppearanceTracker CreateBottomNavViewAppearanceTracker(ShellItem shellItem)
        {
            return new MyBottomNavViewAppearanceTracker(this, shellItem);
        }
    }
}

class MyBottomNavViewAppearanceTracker : ShellBottomNavViewAppearanceTracker
    {
        public MyBottomNavViewAppearanceTracker(IShellContext shellContext, ShellItem shellItem) : base(shellContext, shellItem)
        {
        }
        public override void SetAppearance(BottomNavigationView bottomView, IShellAppearanceElement appearance)
        {
            bottomView.LayoutParameters.Height = 400;
            base.SetAppearance(bottomView, appearance);
        }
    }

[assembly: ExportRenderer(typeof(App.AppShell), typeof(App.iOS.MyShellRenderer))]

namespace App.iOS
{
    public class MyShellRenderer : ShellRenderer
    {

        protected override IShellTabBarAppearanceTracker CreateTabBarAppearanceTracker()
        {
            return new MyCreateTabBarAppearanceTracker();
        }
    }
}

class CreateTabBarAppearanceTracker : ShellTabBarAppearanceTracker
    {
    
        public override void SetAppearance(UITabBarController controller, ShellAppearance appearance)
        {
            UITabBar tabBar = controller.TabBar;
            int tabBarHeight = 100;

            if (tabBar.Frame.Height != tabBarHeight)
            {
                tabBar.Frame = new CGRect(tabBar.Frame.X, tabBar.Frame.Y + (tabBar.Frame.Height - tabBarHeight), tabBar.Frame.Width, tabBarHeight); 
            }
        }
    }

额外费用 您可能缺少了一些可以解释异常大量错误的名称空间

找不到。是否缺少using指令或程序集引用

---

通常人们不会在答案中包含名称空间（

使用

语句），因为大多数情况下名称空间是显而易见的，并且VisualStudioIntelliSense可以轻松处理

只需将光标放在或悬停在带红色下划线的语句上，就会出现一个小的工具提示

---

然后单击“Show potential fix”或其中一个键盘快捷键，选择适当的补丁（通常是建议列表中的第一个），在这种情况下，IntelisSense将自动添加所需的名称空间。

我找到的每个代码示例都排除了using指令。在我的情况下，我需要下面3个我找不到的。感谢@Cfun的回答，上面的代码可以添加：

using Google.Android.Material.BottomNavigation;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;

---

对于iOS，您需要执行类似的操作，“BottomNavigationView”带红色下划线，您知道为什么吗？它给出了一个错误：namespace not found您必须使用Google.Android.Material.BottomNavigation的using语句

通常由IntelliSense处理。OMFG谢谢！！我不知道为什么每个代码expample都会排除using指令……因为大多数情况下，当单击“ctrl+”或“ctrl+enter”时，名称空间是显而易见的，并且由visual studio intlisense处理当光标位于未定义的语句上时，IntelisSense将自动建议并添加所需的名称空间。仅供参考：当有一个带红色下划线的名称，并且您将鼠标悬停在该名称上时，您应该会看到一个带有选项的图标来更正该名称空间。其中一个选项是添加所需的using指令。这就是为什么人们通常不会在一个小代码段中“使用”s的原因。