Convert Date From Timezone

Hi, this is my function

I cannot figure out why i always get jan 1, 2000 [time...]

this is my code

if let thisTime = Int64(time) {
    let date = Date(timeIntervalSince1970: TimeInterval(thisTime) / 1000)
    let dateWithTimezone = convertStringToDateWithTimezone(date)
    print(formatDate(dateWithTimezone, "hh:mm a")!)
}

The date variable is correct but once I use convertStringToDateWithTimezone the result is always jan 1, 2000 [time...] Any idea what could be wrong?

  func convertStringToDateWithTimezone(_ d: Date) -> Date {
    let dateFormatter = DateFormatter()
    dateFormatter.timeZone = TimeZone.current
    return dateFormatter.date(from: (dateFormatter.string(from: d)))!
  }

  func formatDate(_ date: Date?, _ pattern: String) -> String? {
    if let date = date {
      let dateFormatter = DateFormatter()
      dateFormatter.locale = Locale(identifier: "en")
      dateFormatter.dateFormat = pattern
      return dateFormatter.string(from: date)
    }
    return nil
  }