Xamarin 形成如何修复 NavBar
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【中文标题】Xamarin 形成如何修复 NavBar【英文标题】：Xamarin forms how to fix NavBar 【发布时间】：2022-01-13 10:38:40 【问题描述】：Shell.NavBar 有问题，事实上当我打开编辑器时，NavBar 是不可见的。
我的代码页 xaml：
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" xmlns:local="clr-namespace:Corporate_messenger.Service"
x:Class="Corporate_messenger.Views.ChatPage" Shell.BackgroundColor="#04283C" Shell.TitleColor="White" x:Name="set_pqage">
<ContentPage.ToolbarItems>
<ToolbarItem
IconImageSource="audiosocket.png"
x:Name="VoiceRecord"
Clicked="VoiceRecord_Clicked">
</ToolbarItem>
</ContentPage.ToolbarItems>
<Shell.BackButtonBehavior>
<BackButtonBehavior
Command="Binding GoBack">
</BackButtonBehavior>
</Shell.BackButtonBehavior>
<ContentPage.Resources>
<ResourceDictionary>
<DataTemplate
x:Key="FromTemplate">
<ViewCell
x:Name="FromUserCell"
IsEnabled="True" >
<ViewCell.View >
<FlexLayout
JustifyContent="Start">
<Frame
BackgroundColor="#ECEDF1"
CornerRadius="14"
Padding="5,10,10,10"
HasShadow="false"
Margin="10,10,40,0">
<StackLayout
Orientation="Horizontal">
<Label
Text="Binding Message"
IsEnabled="True"
HorizontalTextAlignment="Start"
TextColor="Black"/>
<ImageButton
x:Name="LeftPlay"
Command="Binding Source=x:Reference MyListView,Path=BindingContext.PlayAudioMessage"
CommandParameter="Binding ."
Source="Binding Path=SourceImage,Mode=TwoWay"
IsVisible=" Binding IsAuidoVisible, Mode=TwoWay"
WidthRequest="35" HeightRequest="35"
CornerRadius="50"
BackgroundColor="#0986CE">
</ImageButton>
<Slider
x:Name="LeftSlider"
IsVisible="Binding IsAuidoVisible, Mode=TwoWay"
Maximum="Binding MaximumSlider"
Value="Binding ValueSlider"
IsEnabled="Binding IsEnableSlider"
MaximumTrackColor="Gray"
MinimumTrackColor="#41A9FE"
WidthRequest="150">
</Slider>
<Label
Text="Binding Time_LstMessage"
FontSize="11" MinimumWidthRequest="30"
VerticalTextAlignment="End"
HorizontalTextAlignment="End"
TextColor="DimGray"/>
</StackLayout>
</Frame>
</FlexLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
<!--Правый блок сообщений-->
<DataTemplate
x:Key="ToTemplate">
<ViewCell
x:Name="ToUserCell"
IsEnabled="True">
<FlexLayout
JustifyContent="End" >
<Frame
CornerRadius="14"
BackgroundColor="#CCE4FF"
Padding="5,10,10,10"
Margin="50,10,20,0"
HasShadow="false"
IsClippedToBounds="True">
<StackLayout
Orientation="Horizontal">
<Label
Text="Binding Message"
IsVisible="Binding IsMessageVisible, Mode=TwoWay"
IsEnabled="True"
HorizontalTextAlignment="Start"
TextColor="Black"/>
<ImageButton
x:Name="RightPlay"
Command="Binding Source=x:Reference MyListView,Path=BindingContext.PlayAudioMessage"
CommandParameter="Binding ."
Source="Binding Path=SourceImage,Mode=TwoWay"
IsVisible=" Binding IsAuidoVisible, Mode=TwoWay"
WidthRequest="35"
HeightRequest="35"
CornerRadius="50"
BackgroundColor="#0986CE">
</ImageButton>
<Slider
Maximum="Binding MaximumSlider"
Value="Binding ValueSlider"
IsEnabled="Binding IsEnableSlider"
IsVisible="Binding IsAuidoVisible, Mode=TwoWay"
WidthRequest="150"
MaximumTrackColor="Gray"
MinimumTrackColor="#41A9FE">
</Slider>
<Label
Text="Binding Time_LstMessage"
FontSize="11"
MinimumWidthRequest="30"
VerticalTextAlignment="End"
HorizontalTextAlignment="End"
TextColor="DimGray"/>
</StackLayout>
</Frame>
</FlexLayout>
</ViewCell>
</DataTemplate>
<local:ClassDataTemplateSelector
x:Key="chatDataTemplateSelector"
FromTemplate="StaticResource FromTemplate"
ToTemplate="StaticResource ToTemplate"/>
</ResourceDictionary>
</ContentPage.Resources>
<ContentPage.Content>
<StackLayout>
<ListView
IsRefreshing="Binding IsRefreshing"
RefreshCommand="Binding UpdateList"
ItemTemplate="StaticResource chatDataTemplateSelector"
ItemsSource="Binding LastMessage"
Background="#04283C"
IsPullToRefreshEnabled="True"
RefreshControlColor="Cyan"
Margin="0,0,0,0"
SeparatorColor="Transparent"
x:Name="MyListView"
HasUnevenRows="true"
>
</ListView>
<Grid
RowSpacing="0"
ColumnSpacing="0">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="auto" />
<ColumnDefinition Width="auto" />
</Grid.ColumnDefinitions>
<!--Атрибут для написания сообщения-->
<Editor
Text="Binding Input_message"
Margin="5,0,0,0"
x:Name="MessageEditor"
Keyboard="Chat"
TextColor="Black"
Placeholder="Введите сообщение..."
AutoSize="TextChanges"
Grid.Row="0"
Grid.Column="0">
</Editor>
<ImageButton
Command="Binding SendMessage"
CommandParameter="Binding"
Grid.Row="0"
Grid.Column="1"
Source="send_msg.png"
BackgroundColor="Transparent"
WidthRequest="32" HeightRequest="32"
x:Name="send_message"
/>
<ImageButton
Pressed="mic_message_Pressed"
Released="mic_message_Released"
Grid.Row="0"
Grid.Column="2"
Source="mic.png"
Padding="0"
BackgroundColor="Transparent"
WidthRequest="32"
HeightRequest="32"
x:Name="mic_message"
Margin="0,0,10,0"/>
</Grid>
</StackLayout>
</ContentPage.Content>
</ContentPage>
转到页面代码：
async void Handle_ItemTapped(object sender, ItemTappedEventArgs e)
var v = (ChatListModel)e.Item;
await Navigation.PushAsync(new ChatPage(v.Id, v.Title));
图片示例： enter image description here
enter image description here
【问题讨论】：
此页面是否包含在 NavigationPage 中？ @Jason，我想是的 @Jason，我用 shell 导航 请在 xaml 或 cs 中显示代码 1) shell“路由”声明。 2) 转到该页面的 xaml 或 cs 代码行。去同步？ @ToolmakerSteve，我在页面中添加了跳转代码，看看 【参考方案1】：看起来像这样open issue - Shell - Navigation.PushAsync - Navigation Bar ignored on iOS。有一条评论说现在的解决方法是在每个页面上设置ios:Page.UseSafeArea="true"。
<ContentPage
...
xmlns:ios="clr-namespace:Xamarin.Forms.PlatformConfiguration.iOSSpecific;assembly=Xamarin.Forms.Core"
ios:Page.UseSafeArea="true"
... >
或者为了避免将其添加到每个页面，请创建一个包含这两行的 BaseContentPage 类，然后让您的页面继承自 BaseContentPage 而不是 ContentPage。
【讨论】：
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