问题

I've made a Shared Library Project which defines some often used Views. For example:

<Label x:Name="lblIcon"
    FontSize="30" 
    Margin="20,0,5,0"
    WidthRequest="30"
    VerticalOptions="Center" />

Now to reuse that style, I defined that style inside App.Xaml (still inside the shared Project) and want to reference it via StaticResource:

<Label x:Name="lblIcon"
    Style="{StaticResource TheLabelsStyle}"
    VerticalOptions="Center" />

But this throws an UnhandledException with no further information.

Hopefully someone sees my mistakes and could help me. Thanks in advance!

Edit1

Here is the Style:

<Style x:Key="TheLabelsStyle" TargetType="Label">
    <Setter Property="TextColor" Value="White"/>
    <Setter Property="FontSize" Value="30" />
    <Setter Property="FontAttributes" Value="Bold" />
</Style>

Edit 2

After cleaning and rebuilding the solution multiple times, I figured out the issue comes from the merged Dictionary, especially the FontFamilies.

<!-- App.xaml inside the Shared Project -->
<Application.Resources>

    <!-- Application resource dictionary -->
    <ResourceDictionary>

        <ResourceDictionary.MergedDictionaries>
            <styles:FontFamilies />
            <styles:LabelStyles />
        </ResourceDictionary.MergedDictionaries>

    </ResourceDictionary>
</Application.Resources>

The LabelStyles:

<?xml version="1.0" encoding="UTF-8"?>
<ResourceDictionary xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:styles="clr-namespace:SharpLibrary.Forms.Source.Styles;assembly=SharpLibrary.Forms"
         x:Class="SharpLibrary.Forms.Source.Styles.LabelStyles">

<Style x:Key="HeaderLabel" TargetType="Label">
    <Setter Property="TextColor" Value="White"/>
    <Setter Property="FontSize" Value="30" />
    <Setter Property="FontAttributes" Value="Bold" />
</Style>

<Style x:Key="IconedRoundedEntryIconStyle" TargetType="Label">
    <Setter Property="FontFamily" Value="{DynamicResource FontAwesome}" />
</Style>

</ResourceDictionary>

The FontFamilies:

<?xml version="1.0" encoding="UTF-8"?>
<ResourceDictionary xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         x:Class="SharpLibrary.Forms.Source.Styles.FontFamilies">

<OnPlatform x:Key="FontAwesome" x:TypeArguments="x:String" >
    <OnPlatform.Platforms>
        <On Platform="iOS" Value="FontAwesome"/>
        <On Platform="UWP" Value="ms-appx:///SharpLibrary.Forms/Assets/Fonts/fontawesome-webfont.ttf#FontAwesome"/>
    </OnPlatform.Platforms>
</OnPlatform>

</ResourceDictionary>

But if I do something like...

<Label x:Name="lblIcon"
    FontSize="30" 
    FontFamily="{DynamicResource FontAwesome}"
    Margin="20,0,5,0"
    WidthRequest="30"
    VerticalOptions="Center" />

... this works

来源：https://stackoverflow.com/questions/49669020/xamarin-forms-staticresource-in-shared-library

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