Swift 4, Swift 3 에서 문자열을 Date() 읽고.

Date()를 DateFormatter로 문자열 출력하는 간단한 예제

1. Extensions 필요함

import Foundation

extension DateFormatter {

    convenience init (format: String) {
        self.init()
        dateFormat = format
        locale = Locale.current
    }
}

extension String {

    func toDate (format: String) -> Date? {
        return DateFormatter(format: format).date(from: self)
    }

    func toDateString (inputFormat: String, outputFormat:String) -> String? {
        if let date = toDate(format: inputFormat) {
             return DateFormatter(format: outputFormat).string(from: date)
        }
        return nil
    }
}

extension Date {

    func toString (format:String) -> String? {
        return DateFormatter(format: format).string(from: self)
    }
}

2. 실행 예

var dateString = "14.01.2017T14:54:00"
let format = "dd.MM.yyyy'T'HH:mm:ss"
let date = Date()

print("original String with date:               \(dateString)")
print("date String() to Date():                 \(dateString.toDate(format: format)!)")
print("date String() to formated date String(): \(dateString.toDateString(inputFormat: format, outputFormat: "dd MMMM")!)")
print("format Date():                           \(date.toString(format: "dd MMM HH:mm")!)")

[출처] https://stackoverflow.com/questions/24777496/how-can-i-convert-string-date-to-nsdate