Setting the right resolution for all platforms: iOS, Android, desktop

I am modifying the function initializeCanvas(), from canvas.cs, so that

1) sets the camera size the same size as the resolution
2) calls a custom function that defines several size variables according to resolution

I don't understand this piece of code

if ( $pref::iOS::DeviceType !$= "" )
{
 %resolution = iOSResolutionFromSetting($pref::iOS::DeviceType, $pref::iOS::ScreenOrientation);
}

more specifically, this variable $pref::iOS::DeviceType, is not defined anywhere in the default scripts or the engine code... so how can that function call be ever called ?

here's the modified function

$canvasCreated = false;
function initializeCanvas(%windowName)
{
  // Don't duplicate the canvas.
  if($canvasCreated)
  {
    error("Cannot instantiate more than one canvas!");
    return;
  }

  videoSetGammaCorrection($pref::OpenGL::gammaCorrection);

  if ( !createCanvas(%windowName) )
  {
    error("Canvas creation failed. Shutting down.");
    quit();
  }

  $pref::iOS::ScreenDepth = 32;

  if ( $pref::iOS::DeviceType !$= "" )
  {
    %resolution = iOSResolutionFromSetting($pref::iOS::DeviceType, $pref::iOS::ScreenOrientation);
  }
  else if ($platform $= "Android")
  {
    %resolution = GetAndroidResolution();
  }
  else  //$platform $= "windows" || $platform $= "macos"
  {
    if ($platform_simul $= "iphone") 
      %resolution = "320 480 32";
    else if ($platform_simul $= "ipad") 
      %resolution = "768 1024 32";
    else if ($platform_simul $= "desktop") 
      %resolution = "1024 768 32";
    else %resolution = $pref::Video::windowedRes;     
  }

  setScreenMode( %resolution._0, %resolution._1, %resolution._2, false );
  $canvasCreated = true;

  // Now that we have a Canvas, we need a viewport into the scene.
  // Give it a global name "mainWindow" since we may want to access it directly in our scripts.
  new SceneWindow(mainWindow);
  mainWindow.profile = new GuiControlProfile();
  Canvas.setContent(mainWindow);

  // Set the canvas color
  if ($debug::use_test_scene) Canvas.BackgroundColor = "CornflowerBlue";
  Canvas.UseBackgroundColor = true;

  // Finally, connect our scene into the viewport (or sceneWindow).
  // Note that a viewport comes with a camera built-in.
  mainWindow.setCameraPosition( 0, 0 );
  mainWindow.setCameraSize( %resolution._0, %resolution._1 );
  mainWindow.setUseObjectInputEvents(true);

  $model.set_platform_spaces(%resolution._0, %resolution._1);

  if ($platform $= "Android")
    hideSplashScreen();

  echo ( "platform: ", $platform);
  echo ( "resolution: ", %resolution._0, "x", %resolution._1, "x", %resolution._2);
}