Most Swedish apartments do not have a washing machine even if they are not budget apartments. There is a laundry room usually in the basement of the apartment building that is shared by every resident in the building, even if you don't live in a student dormitory. The room has two or more washing machines, a tumble dryer, and a drying cabinet. What may perplex foreigners is the rule that you need to book the laundry room in advance. Using the room in a time slot you didn't book usually causes hostility from other residents. (When I couldn't finish washing within the booked slot, the resident in the next slot ruthlessly emptied the washing machine before spinning was over and left my soaking-wet clothes nearby, to wash his or her own clothes.)
Time slots, especially the morning and evening ones, are fully booked for next five days or so. It's better to book your first laundry time slot on the day of your arrival. And get used to this way of daily life in Sweden.
Paddy Kelly, an Irish contributor to The Local online newspaper, reports this Swedish custom.