The pair have been working together on the 24-year-old's most recent album, 1989.
Speaking recently of their collaboration, Jack admitted he enjoyed intimate recording sessions with the Love Story singer at his apartment in Brooklyn, New York.
He said: "We like to make music in spaces where people hear music. The idea of making music on studio speakers that project frequencies that no headphones can even reproduce is hilarious.
"We were in studios together, but my favourite experiences with her were in my apartment in Brooklyn, just hanging out with a laptop and a guitar."
The pair - who first met at an awards show a few years ago - worked together on three tracks from the album, I Wish You Would, Out of the Woods and You Are In Love.