Date (String) to Date (ISO) at Swift

Question

I am aware about similar questions, however, I couldn't find this exact one:

In an iOS application, I am receiving a date in the format dd-MM-yyyy HH:mm:ss (i.e. 30-07-2019 12:05:00) in GMT +2h, and I like to convert it to yyyy-MM-dd HH:mm:ss +0000 in GMT ±0h (i.e. 2019-07-30 10:05:00 +0000).

How can I do this?

Answer 1

Firstly create 2 DateFormatter. First dateFormat for create date from dateString. Second dateFormat for create string from created date.

Code:

    let dateString = "30-07-2019 12:05:00"
    let dateFormatForDate = DateFormatter()
    dateFormatForDate.timeZone = TimeZone(abbreviation: "GMT+2")
    dateFormatForDate.dateFormat = "dd-MM-yyyy HH:mm:ss"

    //date
    let date = dateFormatForDate.date(from: dateString)


    let dateFormatForString = DateFormatter()
    dateFormatForString.timeZone = TimeZone(abbreviation: "GMT")
    dateFormatForString.dateFormat = "yyyy-MM-dd HH:mm:ss +0000"

    //string
    let formattedDateString = dateFormatForString.string(from: date!)

Result:

dateString: 30-07-2019 12:05:00
formattedDateString: 2019-07-30 09:05:00 +0000

Answer 2

extension Date {
    func convert(_ from: TimeZone, toTimeZone: TimeZone) -> Date {
        let delta = TimeInterval(toTimeZone.secondsFromGMT() - from.secondsFromGMT())
        return addingTimeInterval(delta)
    }
}

let dateFmt = DateFormatter()
dateFmt.timeZone = TimeZone(abbreviation: "GMT+2")
dateFmt.dateFormat = "dd-MM-yyyy HH:mm:ss"

if let date = dateFmt.date(from: "30-07-2019 12:05:00") {
    let localDate = date.convert(TimeZone(abbreviation: "GMT+02")!, toTimeZone: TimeZone(abbreviation: "GMT+00")!)
}