Inno Setup - Create a checkbox to optionally delete files in a custom page at uninstaller

Question

I created custom pages for an uninstaller using this code: Inno Setup - How to create a OuterNotebook/welcome page in the uninstaller? and I want to create a checkbox that allows me to optionally delete certain files in a custom page (before the uninstallation process). I am trying to use this code:

NewCheckBox1 := TNewCheckBox.Create(UninstallProgressForm);
with NewCheckBox1 do
begin
  Parent := UninstallfirstPage;
  Left := NewStaticText1.Left;
  Top := NewStaticText1.Top + NewStaticText1.Height + 8;
  Width := NewStaticText1.Width;
  Height := ScaleY(30);
  Caption := 'Eliminar partidas guardadas';
end;

But I do not know how to link this code to the action of removing the additional folder in the uninstallation.

For example:

Answer 1

Just check a value of the checkbox in the CurUninstallStepChanged event function and call DelTree function eventually.

var
  NewCheckBox1: TNewCheckBox; { a global variable }

procedure CurUninstallStepChanged(CurUninstallStep: TUninstallStep);
begin
  if CurUninstallStep = usUninstall then { or usPostUninstall }
  begin
    if NewCheckBox1.Checked then
    begin
      Log('Deleting folder');
      if DelTree(ExpandConstant('{userappdata}\My Program'), True, True, True) then
      begin
        Log('Deleted folder');
      end
        else
      begin
        MsgBox('Error deleting folder', mbError, MB_OK);
      end;
    end;
  end;
end;