An international driving licence is effectively a translated appendix to your Swedish licence, which means that you must always have your real driving licence with you as well. You do not need an international driving licence to drive within the EU/EEA. The international driving licence is not issued by the Swedish Transport Agency but by other organisations. The price of an international driving licence is around 200 kr.
There are currently 2 types of international driving licence. One (in accordance with the 1949 Geneva Convention) is valid for 1 year and the other (in accordance with the 1968 Vienna convention) is valid for 3 years.