swift - 如何在 Swift 中以短格式获取当前日期

Question

在下图中你可以看到我写的代码和所有变量的值:

class fun getCurrentShortDate() -> String {
    var todaysDate = NSDate()
    var dateFormatter = NSDateFormatter()
    dateFormatter.dateFormat = "dd-MM-yyyy"
    var DateInFormat = dateFormatter.stringFromDate(todaysDate)

    return DateInFormat
}

Variable values

如您所见，当前日期没有问题，但是当我尝试将 NSDate 更改为字符串时，它就是不会这样做。

Answer 1

Xcode 11 或更高版本 • Swift 5.1 或更高版本

---

extension TimeZone {
    static let gmt = TimeZone(secondsFromGMT: 0)!
}

---

extension Locale {
    static let ptBR = Locale(identifier: "pt_BR")
}

---

extension Formatter {
    static let date = DateFormatter()
}

---

extension Date {
    func localizedDescription(date dateStyle: DateFormatter.Style = .medium,
                              time timeStyle: DateFormatter.Style = .medium,
                              in timeZone: TimeZone = .current,
                              locale: Locale = .current,
                              using calendar: Calendar = .current) -> String {
        Formatter.date.calendar = calendar
        Formatter.date.locale = locale
        Formatter.date.timeZone = timeZone
        Formatter.date.dateStyle = dateStyle
        Formatter.date.timeStyle = timeStyle
        return Formatter.date.string(from: self)
    }
    var localizedDescription: String { localizedDescription() }
}

---

Date().localizedDescription  // "18 Dec 2021 06:43:50"
Date().localizedDescription(in: .gmt)  // "18 Dec 2021 06:43:50" UTC time
Date().localizedDescription(date: .short, time: .short)  // "18/12/21 03:43"
Date().localizedDescription(date: .full, time: .full)  // "Saturday, 18 December 2021 03:43:50 Brasilia Standard Time"
Date().localizedDescription(date: .full, time: .full, in: .gmt)  // "Saturday, 18 December 2021 06:43:50 Greenwich Mean Time"
Date().localizedDescription(date: .full, time: .full, locale: .ptBR)  // "sábado, 18 de dezembro de 2021 03:43:50 Horário Padrão de Brasília"

---

extension Date {

    var fullDate: String { localizedDescription(date: .full, time: .none) }
    var longDate: String { localizedDescription(date: .long, time: .none) }
    var mediumDate: String { localizedDescription(date: .medium, time: .none) }
    var shortDate: String { localizedDescription(date: .short, time: .none) }

    var fullTime: String { localizedDescription(date: .none, time: .full) }
    var longTime: String { localizedDescription(date: .none, time: .long) }
    var mediumTime: String { localizedDescription(date: .none, time: .medium) }
    var shortTime: String { localizedDescription(date: .none, time: .short) }

    var fullDateTime: String { localizedDescription(date: .full, time: .full) }
    var longDateTime: String { localizedDescription(date: .long, time: .long) }
    var mediumDateTime: String { localizedDescription(date: .medium, time: .medium) }
    var shortDateTime: String { localizedDescription(date: .short, time: .short) }
}

---

print(Date().fullDate)  // "Saturday, 18 December 2021\n"
print(Date().shortDate)  // "18/12/21\n"

print(Date().fullTime)  // "03:43:50 Brasilia Standard Time\n"
print(Date().shortTime)  // "03:43\n"

print(Date().fullDateTime)  // "Saturday, 18 December 2021 03:43:50 Brasilia Standard Time\n"
print(Date().shortDateTime)  // "18/12/21 03:43\n"