saving and restoring NSDate with NSUserDefaults

gistfile1.swift

var startTime: NSDate

let defaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(startTime, forKey: "startTime")

// ...

let defaults = NSUserDefaults.standardUserDefaults()
if let object: AnyObject = defaults.objectForKey("startTime") {
  startTime = object as! NSDate
}