Haven't been doing pickup in Sweden, nor have I been in Stockholm.
All I can say is the culture is close to that of Denmark's.
Be prepared for sausage fests if you hit the popular bars and clubs.
Start out early to avoid the negative feelings the girls build up through the night.
Girls are shy and reluctant to talk with strangers. Particularly if they're in big groups, so catch them at the bar table as they're buying something.
Being calm and edgy is what gives the best results outside the dance floor. Since they're shy you'll have to degrade your confidence or act very humble but still remain mysterious and edgy. Direct openers with feelings can be very dangerous. Particularly if she has her friends with her who'll be on edge with it or think you a dork as they aren't used to it at all (cockblock alert).
I dunno if it's worse compared to DK in other countries, but in DK girls are VERY attentive about the slut label, so in most cases you will need to focus on breaking that slowly in your conversations.
Most ppl find their gf/bf/lovers through social circles in these parts (90%+).
Day game I haven't tried yet but I'm certain the success rate will be much much higher.
At least that's how it is in DK and the culture in Sweden is similar to that.
You might think I'm sounding all negative and showcasing victim mentality but I'm not. I'm taking a lot of it as a challenge and pressing on but the views I'm giving are from what I've experienced myself and talked with ppl who came from outside DK, who might've been exchange students and very open minded but they couldn't avoid saying that ppl are more alert and introvert in DK compared to their own countries like Germany and Switzerland.