How to use wpflocalizeextension in Code-Behind?

I regularly use the following native command and have not encountered any errors yet:

LocalizeDictionary.Instance.GetLocalizedObject("keyComesHere", null, LocalizeDictionary.Instance.Culture).ToString()

Of course, before casting to string, you should check for null values.

This is pretty simple. The localization keys are stored as AssemblyName:Resources:KeyName, where Resources is the Resources class name, typically you won't change it to something other.

You can create a simple wrapper to get localized values:

using WPFLocalizeExtension.Extensions;

public static class LocalizationProvider
{
    public static T GetLocalizedValue<T>(string key)
    {
        return LocExtension.GetLocalizedValue<T>(Assembly.GetCallingAssembly().GetName().Name + ":Resources:" + key);
    }
}

So assuming you have created your string resource with the "SignInBtn" key, you can just call:

MessageBox.Show(LocalizationProvider.GetLocalizedValue<string>("SignInBtn"));