How to use a App.config file in WPF applications?

I created an App.config file in my WPF application:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appsettings>
    <add key="xmlDataDirectory" value="c:\testdata"/>
  </appsettings>
</configuration>

Then I try to read the value out with this:

string xmlDataDirectory = ConfigurationSettings.AppSettings.Get("xmlDataDirectory");

But it says this is obsolete and that I should use ConfigurationManager which I can't find, even searching in the class view.

Does anyone know how to use config files like this in WPF?

You have to reference the System.Configuration assembly which is in GAC.

Use of ConfigurationManager is not WPF-specific: it is the privileged way to access configuration information for any type of application.

Please see Microsoft Docs - ConfigurationManager Class for further info.

In my case, I followed the steps below.

App.config

<configuration>  
   <startup> 
       <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
  </startup>

 <appSettings>
   <add key="POCPublishSubscribeQueueName" value="FormatName:Direct=OS:localhost\Private$\POCPublishSubscribe"/>
 </appSettings>

</configuration>

Added System.Configuartion to my project.

Added using System.Configuration statement in file at top.

Then used this statement:

string queuePath = ConfigurationManager.AppSettings["POCPublishSubscribeQueueName"].ToString();