If you are going to work longer than three months to start and run your own business or join as a partner in a company, you must have a residence permit. The permit must be completed before traveling to Sweden. As a self-employed person, you will not be able to get a job elsewhere.
Own entrepreneurs who will work for less than three months in Sweden need no residence permit. For work that lasts less than three months, citizens in some countries must have a visa. Read more about visa during Visit Sweden.