Swopshire, a 6-foot-8 forward, visited Northwestern over the weekend, the source said.
Swopshire will graduate from Louisville in May, but has one year of eligibility remaining after missing his junior season with a groin injury. He will be eligible to play this season.
As a senior, Swopshire averaged 3.3 points per game and played in just over 13 minutes per game on the Cardinals' Final Four team. He was forced into a reserve role behind freshman forward Chane Behanan.