Inno Setup: Check for .NET Desktop Runtime

function CheckDotNetVersion: Boolean;
var
  DotNetVersion: TFindRec;
begin
  Result := False;
  if FindFirst(ExpandConstant('{pf64}')+'\dotnet\host\fxr\*', DotNetVersion) then
  begin
    try
      repeat
        StringChangeEx(DotNetVersion.Name, '.', '', True);
        if (Copy(DotNetVersion.Name, 1, 1) = '8') or ((Copy(DotNetVersion.Name, 1, 1) = '7') and (StrToInt(DotNetVersion.Name) >= 7014)) then
        begin
          Result := True;
          Break;
        end;
      until not FindNext(DotNetVersion);
    finally
      FindClose(DotNetVersion);
    end;
  end;
end;

procedure CurStepChanged(CurStep: TSetupStep);
var
  ResultCode: Integer;
  StatusText: string;
begin
  if (CurStep = ssPostInstall) then
  begin
    if not CheckDotNetVersion then
    begin
      StatusText := WizardForm.StatusLabel.Caption;
      WizardForm.StatusLabel.Caption := CustomMessage('dotNETInstalling');
      WizardForm.ProgressGauge.Style := npbstMarquee;
      try
        if not Exec(ExpandConstant('{tmp}\dotnet.exe'), '/q', '', SW_SHOW, ewWaitUntilTerminated, ResultCode) then
          MsgBox(CustomMessage('dotNETFailed') + IntToStr(ResultCode) + '.', mbError, MB_OK);
      finally
        WizardForm.StatusLabel.Caption := StatusText;
        WizardForm.ProgressGauge.Style := npbstNormal;
      end;
    end;
  end;
end;