Converting date between timezones swift

Simpler version:

extension Date {
    func convertToTimeZone(initTimeZone: TimeZone, timeZone: TimeZone) -> Date {
         let delta = TimeInterval(timeZone.secondsFromGMT(for: self) - initTimeZone.secondsFromGMT(for: self))
         return addingTimeInterval(delta)
    }
}