This IWizard enables your custom template to have files outside of the *proj files and still add them to the file system during the creation of the template with tokenization.

This was initially used to support the React Desktop Apps template which required an additional solution to be created when opening/building the project for Xamarin.Mac as at the time there wasn't another way to support building Xamarin.Mac.

The ExternalTemplateWizard should be used in a multi-project *.vstemplate definition and is designed to create an additional solution and project. For example,

<WizardExtension>
    <Assembly>ServiceStackVS.ExternalTemplateWizard, Version=1.0.0.0, Culture=neutral, PublicKeyToken=b5de165d076e49f5</Assembly>
    <FullClassName>ServiceStackVS.ExternalTemplateWizard.ExternalTemplateWizard</FullClassName>
  </WizardExtension>
  <WizardData>
    ...
    <ExternalTemplate name="ReactJSMac" projFile="ReactJSMac.csproj" solutionFile="ReactJSMac.sln"
                      safeProjectNameReplace="$safeprojectname$.AppMac"
                      outputSolutionName="$saferootprojectname$Mac.sln" 
                      outputProjectName="$saferootprojectname$.AppMac.csproj"
                      >
      <Files>
        <File name="AppDelegate.cs" />
        <File name="AppDelegate.designer.cs" />
        <File name="AppHost.cs" />
        <File name="Info.plist" />
        <File name="Program.cs" />
        <File name="MainMenu.xib" />
        <File name="MainWindow.cs" />
        <File name="MainWindow.designer.cs" />
        <File name="MainWindow.xib" />
        <File name="MainWindowController.cs" />
        <File name="platform.css" />
        <File name="platform.js" />
        <File name="packages.config" />
        <File name="logo.icns" dest="Resources"/>
      </Files>
    </ExternalTemplate>
  </WizardData>

The Files xml is to indicate which files should be processed for token replacement.

Another wizard in this lib is the IIS Express Address Wizard which captures the port number for IIS and replaces the token $iisexpressport$ in specified files in wizard or http://localhost:$iisexpressport$ with full local address. First replacement wins.

If you need to add files for other replacements, just add extra IISExpressAddress in WizardData, for example:

<IISExpressAddress Name="package.json"></IISExpressAddress>

To a project .vstemplate file WizardData. Name is just relative path to file you want to perform the replacement in. Only reason it is done this kinda awkward way is due to URL info not being available until after generation of everything else is complete.