在Innosetup中，如何在安装后替换文件？

[Files]
Source: "path\to\original\file.ext"; DestDir: "{app}"; Flags: ignoreversion

[Code]
procedure CurStepChanged(CurStep: TSetupStep);
var
  OriginalFile: string;
  ReplacementFile: string;
begin
  if CurStep = ssPostInstall then
  begin
    OriginalFile := ExpandConstant('{app}\original\file.ext');
    ReplacementFile := ExpandConstant('{app}\replacement\file.ext');

    if FileExists(OriginalFile) and FileExists(ReplacementFile) then
    begin
      if not DeleteFile(OriginalFile) then
      begin
        MsgBox('Failed to delete original file.', mbError, MB_OK);
        Abort;
      end;

      if not RenameFile(ReplacementFile, OriginalFile) then
      begin
        MsgBox('Failed to replace file.', mbError, MB_OK);
        Abort;
      end;
    end;
  end;
end;