如何在Xamarin表单中创建类似聊天的页脚布局？

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:local="clr-namespace:ChatApp"
             x:Class="ChatApp.MainPage">
    <StackLayout>
        <!-- 聊天内容 -->
        <StackLayout x:Name="ChatContent" VerticalOptions="StartAndExpand">
            <!-- 聊天气泡 -->
            <Frame BackgroundColor="LightGray" Padding="10" Margin="5">
                <Label Text="Hello" />
            </Frame>
            <Frame BackgroundColor="LightGray" Padding="10" Margin="5">
                <Label Text="Hi" />
            </Frame>
        </StackLayout>

        <!-- 输入框和发送按钮 -->
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*" />
                <ColumnDefinition Width="Auto" />
            </Grid.ColumnDefinitions>

            <!-- 输入框 -->
            <Entry Grid.Column="0" Placeholder="输入消息" />

            <!-- 发送按钮 -->
            <Button Grid.Column="1" Text="发送" Clicked="SendMessage" />
        </Grid>
    </StackLayout>
</ContentPage>