How to bind colors in the style resource dictionary?

Question

I'm developing an Xamarin Forms application with a Portable Class Libraries (PCL).

Always, I like to have resources into XAML files as sorted as possible. I have seen that it isn't possible create an XAML resource file directly. A solution for me is removing the App.cs file (on Portable project) and create a Forms Xaml Page as template. I have copied the code from the old App.cs to App.xaml.cs, and then I edited the xaml file.

In the App.xaml file I have defined the color and also the style for a Label. When I bind the color into the style declaration, it fails in runtime.

<Application xmlns="http://xamarin.com/schemas/2014/forms" 
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
         ...>
<Application.Resources>
<ResourceDictionary>

  <!-- LABELS -->
  <Style x:Key="labelProductReference" TargetType="Label" 
         BasedOn="{StaticResource labelBase}" >
    <Setter Property="FontSize" Value="22" />
    <Setter Property="FontAttributes" Value="Bold" />
    <Setter Property="HorizontalOptions" Value="StartAndExpand" />
    <Setter Property="TextColor" Value="{StaticProperty textPrimaryColor}"
  </Style>

   ...

  <!-- COLORS -->
  <Color x:Key="textPrimaryColor">#FFFFFF</Color>

   ...

 </ResourceDictionary>
</Application.Resources>
</Application>

The error says:

Xamarin.Forms.Xaml.XamlParseException: Position 45:38. StaticResource not found for key textPrimaryColor

But If I bind the color where there are the Label into the page (MainPage.xaml), it works:

<Label Text="{Binding Reference}" TextColor="{StaticResource textPrimaryColor}" 
               Style="{StaticResource labelProductReference}" />

How I can set the color for a some control into the xaml style resource declaration?

Answer 1

I have found my problem while I was writing the question.

First, we have to define the colors and then the other elements that we want to use the color.

<!-- COLORS -->
<Color x:Key="textPrimaryColor">#FFFFFF</Color>

<!-- and then, in the same resource file... -->  
<!-- LABELS -->
<Style x:Key="labelProductReference" TargetType="Label" 
     BasedOn="{StaticResource labelBase}" >
   <Setter Property="FontSize" Value="22" />
   <Setter Property="FontAttributes" Value="Bold" />
   <Setter Property="HorizontalOptions" Value="StartAndExpand" />
   <Setter Property="TextColor" Value="{StaticProperty textPrimaryColor}"
</Style>