Sorting NSDictionary by string date value

gistfile1.swift

let rates = responseDictionary["rates"] as NSDictionary
                
                let stringArray = rates.allKeys as [String]
                var dates = Array<NSDate>()
                
                for s in stringArray {
                    dates.append(dateFormater.dateFromString(s)!)
                }
                
                dates.sort({$0.timeIntervalSinceNow < $1.timeIntervalSinceNow})