After earning recognition as a fearless north woods game warden (1926-1935), Swift became deputy director of the old Wisconsin Conservation Department. He rose steadily in the ranks, becoming assistant director in 1943 and director in 1947. He left state service in 1954 and served briefly as assistant director of the US Fish & Wildlife Service before accepting appointment as director of the National Wildlife Federation.
Tough-talking and articulate, Swift was also an excellent writer, authoring many articles and an autobiographical book, A Conservation Saga. Among his many honors were the first Haskell Noyes Award for excellence as a warden (1930) and the Aldo Leopold Medal (1959).