iterator for array structure

[User137]

I have proper destructors for all my classes and at the end of program I .Destroy() them, but do I also have to execute .Free() afterwards?

Free is simply a safe way to call Destroy (it checks first if it exists). So no, don't call both. In the implementation:

procedure TObject.Free;
begin
  // the call via self avoids a warning
  if self<>nil then
    self.destroy;
end;