Swift - How do I display portions of an hour? -

i have label i'm updating every second shows hours 100ths of hour("1.67", etc.). i'm trying show correctly, having trouble.

    second = 781      let timeworked = float(second/3600)      let timeworkedinhours = (string(format:"%.02f", timeworked))      timeworkedlabel.text = "\(timeworkedinhours)" 

i've tried few things, nothing has worked yet. solutions?

i guess second defined int. define double instead. can rid of float cast too:

var second: double = 0 // ... let timeworked = second / 3600.0