你可以使用Swift4或swif5如下所示:

let date = Date()
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd"
let current_date = dateFormatter.string(from: date)
print("current_date-->",current_date)

输出:

2020-03-02

以下代码是最新的swift版本(5):

func getTimestamp()-> String {
     let timestamp = DateFormatter.localizedString(from: Date(), dateStyle: .medium, timeStyle: .short)
     return "\(timestamp)"
}

扩展noiiv的史诗般的简洁解决方案，这里是更简洁的Swift 3/4实现:

斯威夫特3/4

let components = Calendar.current.dateComponents([.hour, .minute], from: Date())
let (hour, minute) = (components.hour, components.minute)

同时，扩展Leo Dabus的扩展，我们可以有:

extension Date {

    func components(_ components: Set<Calendar.Component>) -> DateComponents {
        return Calendar.current.dateComponents(components, from: self)
    }

    func component(_ component: Calendar.Component) -> Int {
        return Calendar.current.component(component, from: self)
    }

    var era: Int { return component(.era) }
    var year: Int { return component(.year) }
    var month: Int { return component(.month) }
    var day: Int { return component(.day) }
    var hour: Int { return component(.hour) }
    var minute: Int { return component(.minute) }
    var second: Int { return component(.second) }
    var weekday: Int { return component(.weekday) }
    var weekdayOrdinal: Int { return component(.weekdayOrdinal) }
    var quarter: Int { return component(.quarter) }
    var weekOfMonth: Int { return component(.weekOfMonth) }
    var weekOfYear: Int { return component(.weekOfYear) }
    var yearForWeekOfYear: Int { return component(.yearForWeekOfYear) }
    var nanosecond: Int { return component(.nanosecond) }
    var calendar: Calendar? { return components([.calendar]).calendar }
    var timeZone: TimeZone? { return components([.timeZone]).timeZone }

}

像这样使用它:

let date = Date()
let (hour, minute) = (date.hour, date.minute)

Swift让创建和使用扩展变得非常容易。我创建了一个sharedCode.swift文件，并在其中放入枚举、扩展名和其他有趣的东西。我创建了一个NSDate扩展来添加一些典型的功能，这是费力和丑陋的输入一遍又一遍:

extension NSDate
{
    func hour() -> Int
    {
        //Get Hour
        let calendar = NSCalendar.currentCalendar()
        let components = calendar.components(.Hour, fromDate: self)
        let hour = components.hour

        //Return Hour
        return hour
    }


    func minute() -> Int
    {
        //Get Minute
        let calendar = NSCalendar.currentCalendar()
        let components = calendar.components(.Minute, fromDate: self)
        let minute = components.minute

        //Return Minute
        return minute
    }

    func toShortTimeString() -> String
    {
        //Get Short Time String
        let formatter = NSDateFormatter()
        formatter.timeStyle = .ShortStyle
        let timeString = formatter.stringFromDate(self)

        //Return Short Time String
        return timeString
    }
}

使用这个扩展，你现在可以做一些事情，如:

        //Get Current Date
        let currentDate = NSDate()

        //Test Extensions in Log
        NSLog("(Current Hour = \(currentDate.hour())) (Current Minute = \(currentDate.minute())) (Current Short Time String = \(currentDate.toShortTimeString()))")

在上午11:51会写出来:

(当前小时= 11)(当前分钟= 51)(当前短时间字符串= 11:51 AM)

您可以在Date上创建一个扩展，这样您就可以轻松地在其他文件中调用它。下面是一个使用计算属性的日期扩展示例。

它会打印出来:“今天，下午4:55”

extension Date {

    var formatter: DateFormatter? {
        let formatter = DateFormatter()
        formatter.dateStyle = .short
        formatter.timeStyle = .short
        formatter.doesRelativeDateFormatting = true

        return formatter
    }
}

使用Date Formatter -Swift 3.0

//Date
let dateFormatter = DateFormatter()
dateFormatter.dateStyle = .medium
let dateString = "Current date is: \(dateFormatter.string(from: Date() as Date))"
labelfordate.text = String(dateString)


//Time    
let timeFormatter = DateFormatter()
timeFormatter.timeStyle = .medium
let timeString = "Current time is: \(timeFormatter.string(from: Date() as Date))"
labelfortime.text = String(timeString)

每秒钟更新一次日期和时间

override func viewDidLoad() {
super.viewDidLoad()

timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(DateAndTime.action), userInfo: nil, repeats: true)

       }

func action()
    {
    //Date
    let dateFormatter = DateFormatter()
    dateFormatter.dateStyle = .medium
    let dateString = "Current date is: \(dateFormatter.string(from: Date() as Date))"
    labelfordate.text = String(dateString)


    //Time
    let timeFormatter = DateFormatter()
    timeFormatter.timeStyle = .medium
    let timeString = "Current time is: \(timeFormatter.string(from: Date() as Date))"
    labelfortime.text = String(timeString)

    }

注意:定时器代码中的DateAndTime是类名。