DateFormatter+Addition.swift

extension DateFormatter {
    class func formatter(dateFormat: String = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'",
                               timeZone: TimeZone? = TimeZone(abbreviation: "UTC")) -> DateFormatter? {
        if let timeZone = timeZone {
            return self.init(dateFormat: dateFormat, timeZone: timeZone)
        }
        return nil
    }
    convenience init(dateFormat: String, timeZone: TimeZone) {
        self.init()
        self.dateFormat = dateFormat
        self.timeZone = timeZone
    }
}

guard let df = DateFormatter.formatter() else {return debugPrint(":( Invalid TimeZone")}
print(df.dateFormat)
print(df.timeZone)