From the Trad to Swing era, the guitarists/banjoist's role remained the same: a quarter note rhythm (four to the bar) that helps to define the pulse created by the bass line. Chord voicings come from the bottom four strings (EADG) and usually consist of only the root, 3rd and 7th. Guitarist, Freddy Green (The Count Basie band) is regarded as having set the template for what a guitarist should play in s Swing band. Freddy's chord voicings consisted of only 3 notes with no chord extensions (root, 3rd and 7th).
Any guitarist who finds themselves in a swing-type big band should learn from Freddy Green!
note: There are other practitioners of Swing Guitar from this era that are worth learning from: Django Reinhardt, Eddie Lang and Lonnie Johnson.