我是Xamarin开发的新手，希望这个看似简单的问题有一个快速的解决办法。
我的环境
- Mac上的Xamarin Studio社区版6.1.3（版本19）
- Xamarin.Android 7.0.2.42
- Xamarin.Ios 10.3.1.7
- Xcode 8.2.1
- Mac OSX 10.12.1
我的问题
我从Visual Studio Online repo得到了一个现有的xaml文件。我为标签控件添加了一个x:name属性，叫做lblSearchText，以便在代码后台中访问它。通过xaml代码后台，我可以按名称添加此控件，没有任何问题。然而，在编译时出现以下错误：
当前上下文中不存在名称'lblSearchText'
我已经确认了以下内容：
- XAML文件上的Build Action是EmbeddedResource
- XAML文件上的Custom Tool属性是MSBuild:UpdateDesignTimeXaml
我的XAML编辑：添加完整的XAML
<?xml version="1.0" encoding="UTF-8" ?>
<common:ContentPage x:Class="MyApp.SearchAuthenticatedPage"
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:common="clr-namespace:MyApp.Common;assembly=MyApp.Common"
xmlns:commonView="clr-namespace:MyApp.Common.Views;assembly=MyApp.Common"
xmlns:help="clr-namespace:MyApp.Helpers;assembly=MyApp"
xmlns:helpersCommon="clr-namespace:MyApp.Helpers;assembly=MyApp.Common"
xmlns:local="clr-namespace:MyApp;assembly=MyApp"
xmlns:sty="clr-namespace:MyApp.Styles;assembly=MyApp">
<common:ContentPage.Resources>
<ResourceDictionary>
<local:DistanceToStringConverter x:Key="DistanceToString" />
<local:StringToHeaderConverter x:Key="StringToHeader" />
<local:StringToUpperConverter x:Key="StringToUpper" />
<local:IsFavoriteToBackgroundColorConverter x:Key="IsFavoriteToBackgroundColor" />
</ResourceDictionary>
</common:ContentPage.Resources>
<RelativeLayout BackgroundColor="White" Padding="0">
<common:SearchBar x:Name="searchBar"
Title="{helpersCommon:Translate searchBarText}"
ClickCommand="{Binding SearchCommand}"
RelativeLayout.HeightConstraint="{ConstraintExpression Type=Constant, Constant=50}"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width}"
RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent, Property=X}"
RelativeLayout.YConstraint="{ConstraintExpression Type=RelativeToParent, Property=Y}" />
<AbsoluteLayout IsVisible="{Binding IsMapVisible}"
RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Constant=-50}"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width}"
RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent, Property=X}"
RelativeLayout.YConstraint="{ConstraintExpression Type=RelativeToParent, Property=Y, Constant=50}">
<commonView:MapView x:Name="map"
WidthRequest="500"
HeightRequest="500"
VerticalOptions="FillAndExpand"
AbsoluteLayout.LayoutBounds="1,1,1,1"
AbsoluteLayout.LayoutFlags="All"
DirectionLocation="{ Binding DirectionLocation}"
IsVisible="{Binding IsMapVisible}"
Location="{Binding CurrentLocation}"
ShowDirection="{ Binding IsShowingDirection}"
Source="{Binding GetMapSource}"
ZoomToLocation="true" />
<Button x:Name="getDirectionButton"
AbsoluteLayout.LayoutBounds=".28,.33,100,30"
AbsoluteLayout.LayoutFlags="PositionProportional"
BackgroundColor="Transparent"
Text="" />
<Button x:Name="storeDetailsButton"
AbsoluteLayout.LayoutBounds=".70,.33,100,30"
AbsoluteLayout.LayoutFlags="PositionProportional"
BackgroundColor="Transparent"
IsVisible="false"
Text="" />
<Button x:Name="phoneButton"
AbsoluteLayout.LayoutBounds=".28,.27,100,20"
AbsoluteLayout.LayoutFlags="PositionProportional"
BackgroundColor="Transparent"
Text="" />
</AbsoluteLayout>
<ListView x:Name="list"
HeightRequest="300"
CachingStrategy="RetainElement"
Footer="{Binding .}"
HasUnevenRows="true"
IsGroupingEnabled="true"
IsVisible="{Binding IsListVisible}"
ItemsSource="{Binding FinalSearchResult}"
RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent, Property=Height, Constant=-47}"
RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent, Property=Width}"
RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent, Property=X}"
RelativeLayout.YConstraint="{ConstraintExpression Type=RelativeToParent, Property=Y, Constant=47}"
SeparatorColor="Transparent"
SeparatorVisibility="None">
<ListView.FooterTemplate>
<DataTemplate>
<ContentView>
<Label x:Name="lblSearchText" <!--- My Control --->
Margin="13, 10"
HorizontalOptions="Center"
IsVisible="{Binding IsEmpty}"
Style="{x:Static sty:Styles.PatientListBigLabelStyle}"
Text="{helpersCommon:Translate searchText}"
VerticalTextAlignment="Center" />
</ContentView>
</DataTemplate>
</ListView.FooterTemplate>
<ListView.GroupHeaderTemplate>
<DataTemplate>
<ViewCell>
<StackLayout BackgroundColor="{Binding Favorite, Converter={StaticResource IsFavoriteToBackgroundColor}}" Padding="13,15">
<Label Style="{x:Static sty:Styles.DarkLabelStyle}" Text="{Binding GroupName}" />
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.GroupHeaderTemplate>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid BackgroundColor="{Binding IsFavorite, Converter={StaticResource IsFavoriteToBackgroundColor}}"
Padding="13,16"
RowSpacing="0">
<Grid.RowDefinitions>
<RowDefinition Height="*" />
<RowDefinition Height="5" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="35" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="30" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="100" />
</Grid.ColumnDefinitions>
<commonView:FavoriteButton Grid.Row="0"
Grid.Column="0"
Margin="0,0,7,0"
ClickCommand="{Binding FavoriteChangedCommand}"
IsFavorite="{Binding IsFavorite}"
Style="{x:Static sty:Styles.FavoriteButtonStyle}" />
<Label Grid.Row="0"
Grid.Column="1"
FontSize="{x:Static sty:Styles.VeryLargeFontSize}"
Style="{x:Static sty:Styles.DarkBoldLabelStyle}"
Text="{Binding ShoppingCenterName}" />
<Label Grid.Row="0"
Grid.Column="2"
FontSize="{x:Static sty:Styles.VeryLargeFontSize}"
Style="{x:Static sty:Styles.DarkBoldRightLabelStyle}"
Text="{Binding DistanceInMilesFromLocation, Converter={StaticResource DistanceToString}}" />
<Label Grid.Row="2"
Grid.Column="1"
IsVisible="{Binding IsAddressVisible}"
Style="{x:Static sty:Styles.DarkLabelStyle}"
Text="{Binding Address}" />
<commonView:UnderlinedButton Grid.Row="2"
Grid.RowSpan="3"
Grid.Column="2"
HeightRequest="35"
Command="{Binding ShowDetailCommand}"
IsVisible="{Binding IsNotSomeMode}"
Style="{x:Static sty:Styles.ListUnderlinedButtonStyle}"
Text="{helpersCommon:Translate detailButtonText}"
TextAligment="TopRight" />
<Label Grid.Row="3"
Grid.Column="1"
VerticalOptions="Start"
IsVisible="{Binding IsAddressVisible}"
Style="{x:Static sty:Styles.DarkLabelStyle}"
Text="{Binding Address2}" />
<commonView:UnderlinedButton Grid.Row="4"
Grid.Column="1"
HeightRequest="35"
HorizontalOptions="StartAndExpand"
Command="{Binding CallCommand}"
Style="{x:Static sty:Styles.ListUnderlinedButtonStyle}"
Text="{Binding Phone}"
TextAligment="TopLeft" />
<commonView:ExtendedButton Grid.Row="4"
Grid.RowSpan="2"
Grid.Column="2"
HorizontalOptions="End"
VerticalOptions="Center"
Command="{Binding SomeCommand}"
IsVisible="{Binding IsSomeMode}"
Style="{x:Static sty:Styles.ActionButtonStyle}"
Text="{helpersCommon:Translate ListSomeButtonText}">
<commonView:ExtendedButton.FontSize>
<OnPlatform x:TypeArguments="x:Double"
Android="11"
iOS="13" />
</commonView:ExtendedButton.FontSize>
</commonView:ExtendedButton>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</RelativeLayout>
</common:ContentPage>
我的代码背后 编辑 - 添加完整的代码
using System.Linq;
using Xamarin.Forms;
using static MyApp.Helpers.UIHelper;
namespace MyApp
{
public partial class SearchAuthenticatedPage : global::MyApp.Common.ContentPage
{
public SearchAuthenticatedPage()
{
InitializeComponent();
lblSearchText.Text = "hello world!";
}
public bool IsMapShowing { get; set; }
protected override void OnBindingContextChanged()
{
base.OnBindingContextChanged();
var vm = BindingContext as BaseListViewModel;
if (vm != null) {
if (!ToolbarItems.Any()) {
SetSwitchToolbarItem();
}
vm.SetSwitchToolbarItem = SetSwitchToolbarItem;
}
getDirectionButton.IsVisible = false;
storeDetailsButton.IsVisible = false;
phoneButton.IsVisible = false;
map.CalloutShownCommand = new Command(OnShowCallout);
map.CalloutHidedCommand = new Command(OnHideCallout);
}
void OnHideCallout()
{
if (Device.OS == TargetPlatform.iOS) {
return;
}
getDirectionButton.IsVisible = false;
phoneButton.IsVisible = false;
}
void OnShowCallout()
{
if (Device.OS == TargetPlatform.iOS) {
return;
}
getDirectionButton.Command = map.ShowDirectionsCommand;
phoneButton.Command = map.PhoneCallCommand;
getDirectionButton.IsVisible = true;
phoneButton.IsVisible = true;
}
public void SetSwitchToolbarItem(bool isMapClicked = false)
{
var switchCommand = (BindingContext as BaseListViewModel)?.ChangeViewCommand;
var switchItem = ToolbarItems.FirstOrDefault(i => i.Priority == 0);
if (switchItem != null) {
switchItem.Text = isMapClicked ? Localize("titleListView") : Localize("titleMapView");
switchItem.Command = switchCommand;
}
else {
ToolbarItems.Add(new ToolbarItem { Text = Localize("titleMapView"), Command = switchCommand });
}
}
}
}
lblSearchText存在于InitializeComponent方法定义中。 - Ehsan Sajjad