I found my accommodation via a website that was recommended to me by the KI contact at the University of Barcelona. I waited for a very long time before I decided on a flat, which was quite stressful. Coming from Stockholm, I thought the the housing market in Barcelona would be as difficult and that I would have to wait for a very long time to get a room and that I might have to stay far away from the city.
But at the end of my search for a flat, I found it to be the complete opposite. I booked a room on the website a week before I arrived to Barcelona and after sending my Bank details and personal information, I had my room in three days.
I ended up finding a room 20 minutes from the city centre with the metro and I shared it with another guy, who owned the flat. My room was somewhat smaller than my room in Sweden(20 square meters) but there was a large living room and kitchen, so it was fine.
I chose the location of the flat to be in the middle between my lab placement in the north-western part of Barcelona and the university in the south of Barcelona city centre. This meant that my commute either way would be 30 minutes.
Overall, I was happy with the area I lived in and it was a big plus that it was close to Sagrada familia.