//试试就明白了
procedure TForm1.Button1Click(Sender: TObject);
begin
if Assigned(GetClass('TForm1')) then
ShowMessage('1-找到')
else ShowMessage('1-没找到');
RegisterClass(TForm1);
if Assigned(GetClass('TForm1')) then
ShowMessage('2-找到')
else ShowMessage('2-没找到');
UnRegisterClass(TForm1);
if Assigned(GetClass('TForm1')) then
ShowMessage('3-找到')
else ShowMessage('3-没找到');
end;