Getting string between exact letters by regex in Swift - swift

Question

I have a String in this format: "2019-03-11T17:04:00+0100". I need to convert that string to the one that will be in this format: "03.11 17:04". I already tried some suggestions for instance this one.

Answer 1

As per my comment, this is a task for DateFormatter rather than RegeX. I threw this together in a playground quickly to demonstrate what I mean.
let inFormatter = DateFormatter()
inFormatter.locale = Locale(identifier: "en_US_POSIX")
inFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZZZZZ"
let input = "2019-03-11T17:04:00+0100"
let dateFromInput = inFormatter.date(from: input)! // This should be unwrapped properly in your code.
let outFormatter = DateFormatter()
outFormatter.locale = Locale(identifier: "en_US_POSIX")
outFormatter.dateFormat = "MM. dd HH:mm"
let output = outFormatter.string(from: dateFromInput)
print(output) // Prints 03. 11 16:04.
The premise is that you provide a format for which to parse the input string against, this is transcoded to a Date object which you can then transcode to your desired output format with a second DateFormatter.
EDIT:
As pointed out by #user28434, the input you are passing in looks like CET (Central European Time); When I configure the output DateFormatter, I do not specify a time zone so it defaults to my local time zone, GMT (Greenwich Mean Time). This would obviously cause the output to be different based on the location of the user in the world, which should be expected/desired. But it's worth highlighting. You can use outFormatter.timeZone = TimeZone(identifier: "CET") to force a CET output.

Answer 2

You can use DateFormatter instead of regex,
first, convert the given string to a date with the string format,
then convert the resulted date to a string with the desired format.
func convertISO8601DateStringToDate(dateStr: String) -> Date? {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZ"
return dateFormatter.date(from: dateStr)
}
func convertDateToReadableOutput(date: Date) -> String {
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "MM.dd HH:mm"
return dateFormatter.string(from: date)
}
you can use these two methods as below:
if let date = stringToDateConverter(dateStr: "2019-03-11T17:04:00+0100") {
print(dateToStringConverter(date: date))
}