如何使用Swift获取当天的时间？

Question

我怎么能在斯威夫特那里得到一天的时间.我曾尝试NSCalendar和NSDateComponents,但我怕我刚开始用斯威夫特.

Answer 1

Swift 4和Swift 3

let hour = Calendar.current.component(.hour, from: Date())

 

或者,如果您对12 hour AM/PM日期格式感兴趣,请使用NSDateFormatter

let formatter = DateFormatter()
formatter.dateFormat = "hh a" // "a" prints "pm" or "am"
let hourString = formatter.string(from: Date()) // "12 AM"

如果您需要分钟,秒和其他,请执行以下操作

let date = Date() // save date, so all components use the same date
let calendar = Calendar.current // or e.g. Calendar(identifier: .persian)

let hour = calendar.component(.hour, from: date)
let minute = calendar.component(.minute, from: date)
let second = calendar.component(.second, from: date)

查看Apple文档中的可用组件:

.era, .year, .month, .day, .hour, .minute, .second,
.weekday, .weekdayOrdinal, .quarter, weekOfMonth, .weekOfYear,
.yearForWeekOfYear, .nanosecond, .calendar, .timezone

Swift 2.0

let hour = NSCalendar.currentCalendar().component(.Hour, fromDate: NSDate())

Swift 1.0

let hour = NSCalendar.currentCalendar().component(.CalendarUnitHour, fromDate: NSDate())

Answer 2

斯威夫特3:

let date = Date()// Aug 25, 2017, 11:55 AM
let calendar = Calendar.current

let hour = calendar.component(.hour, from: date) //11
let minute = calendar.component(.minute, from: date) //55
let sec = calendar.component(.second, from: date) //33
let weekDay = calendar.component(.weekday, from: date) //6 (Friday) 

从以下API获取任何组件

public enum Component {
    case era
    case year
    case month
    case day
    case hour
    case minute
    case second
    case weekday
    case weekdayOrdinal
    case quarter
    case weekOfMonth
    case weekOfYear
    case yearForWeekOfYear
    case nanosecond
    case calendar
    case timeZone
}

斯威夫特2:

let currentHour = NSCalendar.currentCalendar().component(.Hour, fromDate: NSDate())

这可能就足够了:

let currentDate = NSDate() // You can input the custom as well 
let calendar = NSCalendar.currentCalendar()
let components = calendar.components(.CalendarUnitHour | .CalendarUnitMinute, fromDate:  currentDate)
let currentHour = components.hour // You can play around with the ""components""

Answer 3

如果你想要一个字符串中的当前小时,这是我能想到的简短和可读.

let formatter = NSDateFormatter()
formatter.dateFormat = "HH"

let timeString = formatter.stringFromDate(NSDate())