如何在Xamarin的主详细信息页面上的页面项目上添加下拉列表？

Question

看起来像这样

我一直在研究医疗应用，并使用MasterDetailPage将所有导航放到一个地方。但它太多了，所以我想把它分成一个。我想到了每个页面项目的下拉菜单。我一直在网上搜索实现它，但我无法弄明白。这是Android上的Xamarin，我想做一个类似于上图的下拉菜单。

这是我目前在C＃上的代码

namespace MasterDetailPageNavigation
{
    public partial class MasterPage : ContentPage
    {
        public ListView ListView { get { return listView; } }

        public MasterPage ()
        {
            InitializeComponent ();
            BackgroundColor = Color.FromHex ("ffffff");
            var masterPageItems = new List<MasterPageItem> ();
            masterPageItems.Add (new MasterPageItem {
                Title = "DashBoard",
                TargetType = typeof(DashBoard)
            });
            masterPageItems.Add (new MasterPageItem {
                Title = "Schedules",
                TargetType = typeof(SchedulesCS)
            });

            masterPageItems.Add (new MasterPageItem {
                Title = "Master Data",
                TargetType = typeof(MasterDataCS)
            });

            masterPageItems.Add (new MasterPageItem {
                Title = "Audit Trail",
                TargetType = typeof(AuditTrailCS)
            });

            listView.ItemsSource = masterPageItems;
        }
    }
}

对于xaml

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" 
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
             x:Class="MasterDetailPageNavigation.MasterPage"
             Padding="0,40,0,0"
             Icon="hamburger.png"
             Title="Medical">
    <ContentPage.Content>
        <StackLayout VerticalOptions="FillAndExpand">
            <ListView x:Name="listView" VerticalOptions="FillAndExpand" SeparatorVisibility="None">
                <ListView.ItemTemplate>
                    <DataTemplate>
                        <ImageCell Text="{Binding Title}" ImageSource="{Binding IconSource}" />
                    </DataTemplate>
                </ListView.ItemTemplate>
            </ListView>
        </StackLayout>
    </ContentPage.Content>
</ContentPage>

你是怎么做到的？