//AVAILABLE STRING FORMATS FOR DATEFORMAT

Wednesday, Sep 12, 2018           --> EEEE, MMM d, yyyy
09/12/2018                        --> MM/dd/yyyy
09-12-2018 14:11                  --> MM-dd-yyyy HH:mm
Sep 12, 2:11 PM                   --> MMM d, h:mm a
September 2018                    --> MMMM yyyy
Sep 12, 2018                      --> MMM d, yyyy
Wed, 12 Sep 2018 14:11:54 +0000   --> E, d MMM yyyy HH:mm:ss Z
2018-09-12T14:11:54+0000          --> yyyy-MM-dd'T'HH:mm:ssZ
12.09.18                          --> dd.MM.yy
10:41:02.112                      --> HH:mm:ss.SSS

func getTimeStampDateString() -> String {
        let date = Date(timeIntervalSinceNow: self.doubleValue)
        let dateFormatter = DateFormatter()
        dateFormatter.timeZone = TimeZone(abbreviation: "GMT")
        dateFormatter.locale = NSLocale.current
        dateFormatter.dateFormat = "d MMM HH:mm:ss"
        let strDate = dateFormatter.string(from: date)
        return strDate
    }