Barcelona is growing to become one of the top 5 European IT hubs. If you attend technical meetups, literally every company that is represented there is looking to recruit. So there is continuous high demand for IT professionals, without a doubt.
In terms of salary, the average is around 35-40K / year, before taxes. It can go up to 50, 60 and I've seen even 70K, depending on the company, requirements, etc. But the higher it goes, the fewer the opportunities.