Xamarin Forms：更改页面时菜单消失

问题描述

我有一个应用程序，它有两个页面：主页和设置。

我遇到的问题是，当我在这些页面之间导航时，我的侧边菜单突然消失了。

我已经尝试了“任何事情”，我的意思是我已经尝试了所有我能做的事情，但结果还是一样。

This is the view before I navigate to SettingsPage

This is the view after I navigate to SettingsPage

如您所见，菜单消失了。

代码：

<?xml version="1.0" encoding="UTF-8"?>
<Shell xmlns="http://xamarin.com/schemas/2014/forms" 
       xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
       xmlns:local="clr-namespace:MyTestApplication.Views"
       xmlns:viewmodels="clr-namespace:MyTestApplication.viewmodels;assembly=MyTestApplication"
       Title="MyTestApplication"
       x:Class="MyTestApplication.AppShell">


    
    <Shell.Resources>
        <ResourceDictionary>
            <Style x:Key="BaseStyle" targettype="Element">
                <Setter Property="Shell.BackgroundColor" Value="{StaticResource Primary}" />
                <Setter Property="Shell.ForegroundColor" Value="White" />
                <Setter Property="Shell.TitleColor" Value="White" />
                <Setter Property="Shell.disabledColor" Value="#B4FFFFFF" />
                <Setter Property="Shell.UnselectedColor" Value="#95FFFFFF" />
                <Setter Property="Shell.TabBarBackgroundColor" Value="{StaticResource Primary}" />
                <Setter Property="Shell.TabBarForegroundColor" Value="White"/>
                <Setter Property="Shell.TabBarUnselectedColor" Value="#95FFFFFF"/>
                <Setter Property="Shell.TabBarTitleColor" Value="White"/>
            </Style>
            <Style targettype="TabBar" BasedOn="{StaticResource BaseStyle}" />
            <Style targettype="FlyoutItem" BasedOn="{StaticResource BaseStyle}" />
            <Style targettype="local:SettingsPage" BasedOn="{StaticResource BaseStyle}" />

  
          
            <Style Class="MenuItemLayoutStyle" targettype="Layout" ApplyToDerivedTypes="True">
                <Setter Property="visualstatemanager.VisualStateGroups">
                    <VisualStateGroupList>
                        <VisualStateGroup x:Name="CommonStates">
                            <VisualState x:Name="normal">
                                <VisualState.Setters>
                                    <Setter TargetName="FlyoutItemLabel" Property="Label.TextColor" Value="{StaticResource Primary}" />
                                </VisualState.Setters>
                            </VisualState>
                        </VisualStateGroup>
                    </VisualStateGroupList>
                </Setter>
            </Style>
        </ResourceDictionary>
    </Shell.Resources>

  <Shell.FlyoutContentTemplate>
        <DataTemplate>
            <StackLayout>
                <ListView x:Name="MenuItemsListView"
                          SeparatorVisibility="None"
                          HasUnevenRows="true"
                          ItemsSource="{Binding FlyoutItems}" ItemTapped="Settings_Button">
                    <ListView.Header>
                        <Grid BackgroundColor="Rosybrown">
                            <Grid.ColumnDeFinitions>
                                <ColumnDeFinition Width="10"/>
                                <ColumnDeFinition Width="*"/>
                                <ColumnDeFinition Width="10"/>
                            </Grid.ColumnDeFinitions>
                            <Grid.RowDeFinitions>
                                <RowDeFinition Height="30"/>
                                <RowDeFinition Height="80"/>
                                <RowDeFinition Height="Auto"/>
                                <RowDeFinition Height="10"/>
                            </Grid.RowDeFinitions>
                            <Label Grid.Row="2" Grid.Column="1"
                                   TextColor="#d7d9b4"
                                   Text="{Binding Title}"
                                   FontSize="24"/>
                        </Grid>
                    </ListView.Header>
                    <ListView.ItemTemplate>
                        <DataTemplate>
                            <ViewCell>
                                <StackLayout Padding="15,10"
                                             HorizontalOptions="FillAndExpand">
                                    <Label VerticalOptions="FillAndExpand" 
                                           VerticalTextAlignment="Center"
                                           Text="{Binding Type}"
                                           TextColor="Black"
                                           FontSize="20"/>
                                </StackLayout>
                            </ViewCell>
                        </DataTemplate>

                        
                    </ListView.ItemTemplate>
                </ListView>

                <ListView x:Name="MenuItemsListView2"
                          SeparatorVisibility="None"
                          HasUnevenRows="true"
                          ItemsSource="{Binding FlyoutItems2}" ItemTapped="Home_Button">
                    <ListView.ItemTemplate>
                        <DataTemplate>
                            <ViewCell>
                                <StackLayout Padding="15,10"
                                             HorizontalOptions="FillAndExpand">
                                    <Label VerticalOptions="FillAndExpand"
                                           VerticalTextAlignment="Center"
                                           Text="{Binding Type}"
                                           TextColor="Black"
                                           FontSize="20"/>
                                </StackLayout>
                            </ViewCell>
                        </DataTemplate>
                    </ListView.ItemTemplate>
                </ListView>

            </StackLayout>
        </DataTemplate>

      
    </Shell.FlyoutContentTemplate>

        <FlyoutItem Title="Home" Icon="home.png">
            <ShellContent Route="MainPage" ContentTemplate="{DataTemplate local:MainPage}"/>
        </FlyoutItem>
        <FlyoutItem Title="Settings" Icon="setting.png">
            <ShellContent Route="SettingsPage" ContentTemplate="{DataTemplate local:SettingsPage}" />
        </FlyoutItem>

    <TabBar >
        <ShellContent Route="LoginPage" ContentTemplate="{DataTemplate local:LoginPage}" />
    </TabBar>

</Shell>

欢迎提出任何想法！

谢谢！

解决方法

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