Date to milliseconds and back to date in Swift

Question

I am taking the current time, in UTC, and putting it in nanaoseconds and then I need to take the nanoseconds and go back to a date in local time. I am able to do get the tim

Answer 1

Heres a simple solution in Swift 5/iOS 13.

extension Date {
    
    func toMilliseconds() -> Int64 {
        Int64(self.timeIntervalSince1970 * 1000)
    }

    init(milliseconds:Int) {
        self = Date().advanced(by: TimeInterval(integerLiteral: Int64(milliseconds / 1000)))
    }
}

This however assumes you have calculated the difference between UTF time and local time and adjusted and accounted for in the milliseconds. For that look to calendar

var cal = Calendar.current
cal.timeZone = TimeZone(abbreviation: "UTC")!
let difference = cal.compare(dateGiven, to: date, toGranularity: .nanosecond)