Swift-Date Extension

///  Day name format.
///
/// - threeLetters: 3 letter day abbreviation of day name.
/// - oneLetter: 1 letter day abbreviation of day name.
/// - full: Full day name.
public enum DayNameStyle {
    case threeLetters
    case oneLetter
    case full
}

/// Month name format.
///
/// - threeLetters: 3 letter month abbreviation of month name.
/// - oneLetter: 1 letter month abbreviation of month name.
/// - full: Full month name.
public enum MonthNameStyle {
    case threeLetters
    case oneLetter
    case full
}

属性

当前calendar

extension Date {
    public var calendar: Calendar {
        return Calendar.current
    }
}

时代

extension Date {
    ///
    ///     Date().era -> 1
    ///
    public var era: Int {
        return Calendar.current.component(.era, from: self)
    }
}

季度

extension Date {
    ///
    ///     Date().quarter -> 3 // date in third quarter of the year.
    ///
    public var quarter: Int {
        let month = Double(Calendar.current.component(.month, from: self))
        let numberOfMonths = Double(Calendar.current.monthSymbols.count)
        let numberOfMonthsInQuarter = numberOfMonths / 4
        return Int(ceil(month/numberOfMonthsInQuarter))
    }
}

一年中的第几周

extension Date {
    ///
    ///     Date().weekOfYear -> 2 // second week in the year.
    ///
    public var weekOfYear: Int {
        return Calendar.current.component(.weekOfYear, from: self)
    }
}

一月中的第几周

extension Date {
    ///
    ///     Date().weekOfMonth -> 3 // date is in third week of the month.
    ///
    public var weekOfMonth: Int {
        return Calendar.current.component(.weekOfMonth, from: self)
    }
}

年

extension Date {
    ///
    ///     Date().year -> 2017
    ///
    ///     var someDate = Date()
    ///     someDate.year = 2000 // sets someDate's year to 2000
    ///
    public var year: Int {
        get {
            return Calendar.current.component(.year, from: self)
        }
        set {
            guard newValue > 0 else { return }
            let currentYear = Calendar.current.component(.year, from: self)
            let yearsToAdd = newValue - currentYear
            if let date = Calendar.current.date(byAdding: .year, value: yearsToAdd, to: self) {
                self = date
            }
        }
    }
}

月

extension Date {
    ///
    ///     Date().month -> 1
    ///
    ///     var someDate = Date()
    ///     someDate.month = 10 // sets someDate's month to 10.
    ///
    public var month: Int {
        get {
            return Calendar.current.component(.month, from: self)
        }
        set {
            let allowedRange = Calendar.current.range(of: .month, in: .year, for: self)!
            guard allowedRange.contains(newValue) else { return }
    
            let currentMonth = Calendar.current.component(.month, from: self)
            let monthsToAdd = newValue - currentMonth
            if let date = Calendar.current.date(byAdding: .month, value: monthsToAdd, to: self) {
                self = date
            }
        }
    }
}

天

extension Date {
    ///
    ///     Date().day -> 12
    ///
    ///     var someDate = Date()
    ///     someDate.day = 1 // sets someDate's day of month to 1.
    ///
    public var day: Int {
        get {
            return Calendar.current.component(.day, from: self)
        }
        set {
            let allowedRange = Calendar.current.range(of: .day, in: .month, for: self)!
            guard allowedRange.contains(newValue) else { return }
    
            let currentDay = Calendar.current.component(.day, from: self)
            let daysToAdd = newValue - currentDay
            if let date = Calendar.current.date(byAdding: .day, value: daysToAdd, to: self) {
                self = date
            }
        }
    }
}

星期几

extension Date {
    ///
    ///     Date().weekday -> 5 // fifth day in the current week.
    ///
    public var weekday: Int {
        return Calendar.current.component(.weekday, from: self)
    }
}

当前时间的小时

extension Date {
    ///
    ///     Date().hour -> 17 // 5 pm
    ///
    ///     var someDate = Date()
    ///     someDate.hour = 13 // sets someDate's hour to 1 pm.
    ///
    public var hour: Int {
        get {
            return Calendar.current.component(.hour, from: self)
        }
        set {
            let allowedRange = Calendar.current.range(of: .hour, in: .day, for: self)!
            guard allowedRange.contains(newValue) else { return }
    
            let currentHour = Calendar.current.component(.hour, from: self)
            let hoursToAdd = newValue - currentHour
            if let date = Calendar.current.date(byAdding: .hour, value: hoursToAdd, to: self) {
                self = date
            }
        }
    }
}

当前时间的分钟

extension Date {
    ///
    ///     Date().minute -> 39
    ///
    ///     var someDate = Date()
    ///     someDate.minute = 10 // sets someDate's minutes to 10.
    ///
    public var minute: Int {
        get {
            return Calendar.current.component(.minute, from: self)
        }
        set {
            let allowedRange = Calendar.current.range(of: .minute, in: .hour, for: self)!
            guard allowedRange.contains(newValue) else { return }
    
            let currentMinutes = Calendar.current.component(.minute, from: self)
            let minutesToAdd = newValue - currentMinutes
            if let date = Calendar.current.date(byAdding: .minute, value: minutesToAdd, to: self) {
                self = date
            }
        }
    }
}

当前时间的秒

extension Date {
///
    ///     Date().second -> 55
    ///
    ///     var someDate = Date()
    ///     someDate.second = 15 // sets someDate's seconds to 15.
    ///
    public var second: Int {
        get {
            return Calendar.current.component(.second, from: self)
        }
        set {
            let allowedRange = Calendar.current.range(of: .second, in: .minute, for: self)!
            guard allowedRange.contains(newValue) else { return }
    
            let currentSeconds = Calendar.current.component(.second, from: self)
            let secondsToAdd = newValue - currentSeconds
            if let date = Calendar.current.date(byAdding: .second, value: secondsToAdd, to: self) {
                self = date
            }
        }
    }
}

纳秒

extension Date {
    ///
    ///     Date().nanosecond -> 981379985
    ///
    ///     var someDate = Date()
    ///     someDate.nanosecond = 981379985 // sets someDate's seconds to 981379985.
    ///
    public var nanosecond: Int {
        get {
            return Calendar.current.component(.nanosecond, from: self)
        }
        set {
            let allowedRange = Calendar.current.range(of: .nanosecond, in: .second, for: self)!
            guard allowedRange.contains(newValue) else { return }
    
            let currentNanoseconds = Calendar.current.component(.nanosecond, from: self)
            let nanosecondsToAdd = newValue - currentNanoseconds
    
            if let date = Calendar.current.date(byAdding: .nanosecond, value: nanosecondsToAdd, to: self) {
                self = date
            }
        }
    }
}

毫秒

extension Date {
    ///
    ///     Date().millisecond -> 68
    ///
    ///     var someDate = Date()
    ///     someDate.millisecond = 68 // sets someDate's nanosecond to 68000000.
    ///
    public var millisecond: Int {
        get {
            return Calendar.current.component(.nanosecond, from: self) / 1000000
        }
        set {
            let nanoSeconds = newValue * 1000000
            let allowedRange = Calendar.current.range(of: .nanosecond, in: .second, for: self)!
            guard allowedRange.contains(nanoSeconds) else { return }
    
            if let date = Calendar.current.date(bySetting: .nanosecond, value: nanoSeconds, of: self) {
                self = date
            }
        }
    }
}

是否是将来时间

extension Date {
    ///
    ///     Date(timeInterval: 100, since: Date()).isInFuture -> true
    ///
    public var isInFuture: Bool {
        return self > Date()
    }
}

是否是过去时间

extension Date {
    ///
    ///     Date(timeInterval: -100, since: Date()).isInPast -> true
    ///
    public var isInPast: Bool {
        return self < Date()
    }
}

是否在今天

extension Date {
    ///
    ///     Date().isInToday -> true
    ///
    public var isInToday: Bool {
        return Calendar.current.isDateInToday(self)
    }
}

是否是在昨天

extension Date {
    ///
    ///     Date().isInYesterday -> false
    ///
    public var isInYesterday: Bool {
        return Calendar.current.isDateInYesterday(self)
    }
}

是否是在明天

extension Date {
    ///
    ///     Date().isInTomorrow -> false
    ///
    public var isInTomorrow: Bool {
        return Calendar.current.isDateInTomorrow(self)
    }
}

是否在周末期间

extension Date {
    public var isInWeekend: Bool {
        return Calendar.current.isDateInWeekend(self)
    }
}

是否在工作日内

extension Date {
    public var isWorkday: Bool {
        return !Calendar.current.isDateInWeekend(self)
    }
}

是否在当前周内

extension Date {
    public var isInCurrentWeek: Bool {
        return Calendar.current.isDate(self, equalTo: Date(), toGranularity: .weekOfYear)
    }
}

是否在当前月内

extension Date {
    public var isInCurrentMonth: Bool {
        return Calendar.current.isDate(self, equalTo: Date(), toGranularity: .month)
    }
}

是否在当前年内

extension Date {
    public var isInCurrentYear: Bool {
        return Calendar.current.isDate(self, equalTo: Date(), toGranularity: .year)
    }
}

ISO8601格式

extension Date {
    /// ISO8601 string of format (yyyy-MM-dd'T'HH:mm:ss.SSS) from date.
    ///
    ///     Date().iso8601String -> "2017-01-12T14:51:29.574Z"
    ///
    public var iso8601String: String {
        // https://github.com/justinmakaila/NSDate-ISO-8601/blob/master/NSDateISO8601.swift
        let dateFormatter = DateFormatter()
        dateFormatter.locale = Locale(identifier: "en_US_POSIX")
        dateFormatter.timeZone = TimeZone(abbreviation: "GMT")
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS"
    
        return dateFormatter.string(from: self).appending("Z")
}
}

最近的5整数倍分钟时间

extension Date {
    ///
    ///     var date = Date() // "5:54 PM"
    ///     date.minute = 32 // "5:32 PM"
    ///     date.nearestFiveMinutes // "5:30 PM"
    ///
    ///     date.minute = 44 // "5:44 PM"
    ///     date.nearestFiveMinutes // "5:45 PM"
    ///
    public var nearestFiveMinutes: Date {
        var components = Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second, .nanosecond], from: self)
        let min = components.minute!
        components.minute! = min % 5 < 3 ? min - min % 5 : min + 5 - (min % 5)
        components.second = 0
        components.nanosecond = 0
        return Calendar.current.date(from: components)!
    }
}

最近的10整数倍分钟时间

extension Date {
    ///
    ///     var date = Date() // "5:57 PM"
    ///     date.minute = 34 // "5:34 PM"
    ///     date.nearestTenMinutes // "5:30 PM"
    ///
    ///     date.minute = 48 // "5:48 PM"
    ///     date.nearestTenMinutes // "5:50 PM"
    ///
    public var nearestTenMinutes: Date {
        var components = Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second, .nanosecond], from: self)
        let min = components.minute!
        components.minute? = min % 10 < 6 ? min - min % 10 : min + 10 - (min % 10)
        components.second = 0
        components.nanosecond = 0
        return Calendar.current.date(from: components)!
    }
}

最近刻度时间

extension Date {
    ///
    ///     var date = Date() // "5:57 PM"
    ///     date.minute = 34 // "5:34 PM"
    ///     date.nearestQuarterHour // "5:30 PM"
    ///
    ///     date.minute = 40 // "5:40 PM"
    ///     date.nearestQuarterHour // "5:45 PM"
    ///
    public var nearestQuarterHour: Date {
        var components = Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second, .nanosecond], from: self)
        let min = components.minute!
        components.minute! = min % 15 < 8 ? min - min % 15 : min + 15 - (min % 15)
        components.second = 0
        components.nanosecond = 0
        return Calendar.current.date(from: components)!
    }
}

最近半小时时间

extension Date {
    ///
    ///     var date = Date() // "6:07 PM"
    ///     date.minute = 41 // "6:41 PM"
    ///     date.nearestHalfHour // "6:30 PM"
    ///
    ///     date.minute = 51 // "6:51 PM"
    ///     date.nearestHalfHour // "7:00 PM"
    ///
    public var nearestHalfHour: Date {
        var components = Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second, .nanosecond], from: self)
        let min = components.minute!
        components.minute! = min % 30 < 15 ? min - min % 30 : min + 30 - (min % 30)
        components.second = 0
        components.nanosecond = 0
        return Calendar.current.date(from: components)!
    }
}

最近小时时间

extension Date {
    ///
    ///     var date = Date() // "6:17 PM"
    ///     date.nearestHour // "6:00 PM"
    ///
    ///     date.minute = 36 // "6:36 PM"
    ///     date.nearestHour // "7:00 PM"
    ///
    public var nearestHour: Date {
        let min = Calendar.current.component(.minute, from: self)
        let components: Set = [.year, .month, .day, .hour]
        let date = Calendar.current.date(from: Calendar.current.dateComponents(components, from: self))!
    
        if min < 30 {
            return date
        }
        return Calendar.current.date(byAdding: .hour, value: 1, to: date)!
    }
}

时区

extension Date {
    ///
    ///     Date().timeZone -> Europe/Istanbul (current)
    ///
    public var timeZone: TimeZone {
        return Calendar.current.timeZone
    }
}

unix时间戳

extension Date {
    ///
    ///     Date().unixTimestamp -> 1484233862.826291
    ///
    public var unixTimestamp: Double {
        return timeIntervalSince1970
    }
}

方法

根据Calendar.Component更改日期

extension Date {
    ///
    ///     let date = Date() // "Jan 12, 2017, 7:07 PM"
    ///     let date2 = date.adding(.minute, value: -10) // "Jan 12, 2017, 6:57 PM"
    ///     let date3 = date.adding(.day, value: 4) // "Jan 16, 2017, 7:07 PM"
    ///     let date4 = date.adding(.month, value: 2) // "Mar 12, 2017, 7:07 PM"
    ///     let date5 = date.adding(.year, value: 13) // "Jan 12, 2030, 7:07 PM"
    ///
    /// - Parameters:
    ///   - component: component type.
    ///   - value: multiples of components to add.
    /// - Returns: original date + multiples of component added.
    public func adding(_ component: Calendar.Component, value: Int) -> Date {
        return Calendar.current.date(byAdding: component, value: value, to: self)!
    }
}

根据Calendar.Component更改日期

extension Date {
    ///
    ///     var date = Date() // "Jan 12, 2017, 7:07 PM"
    ///     date.add(.minute, value: -10) // "Jan 12, 2017, 6:57 PM"
    ///     date.add(.day, value: 4) // "Jan 16, 2017, 7:07 PM"
    ///     date.add(.month, value: 2) // "Mar 12, 2017, 7:07 PM"
    ///     date.add(.year, value: 13) // "Jan 12, 2030, 7:07 PM"
    ///
    /// - Parameters:
    ///   - component: component type.
    ///   - value: multiples of compnenet to add.
    public mutating func add(_ component: Calendar.Component, value: Int) {
        if let date = Calendar.current.date(byAdding: component, value: value, to: self) {
            self = date
        }
    }
}

改变Calendar.Component的值

extension Date {
    ///
    ///     let date = Date() // "Jan 12, 2017, 7:07 PM"
    ///     let date2 = date.changing(.minute, value: 10) // "Jan 12, 2017, 6:10 PM"
    ///     let date3 = date.changing(.day, value: 4) // "Jan 4, 2017, 7:07 PM"
    ///     let date4 = date.changing(.month, value: 2) // "Feb 12, 2017, 7:07 PM"
    ///     let date5 = date.changing(.year, value: 2000) // "Jan 12, 2000, 7:07 PM"
    ///
    /// - Parameters:
    ///   - component: component type.
    ///   - value: new value of compnenet to change.
    /// - Returns: original date after changing given component to given value.
    public func changing(_ component: Calendar.Component, value: Int) -> Date? {
        switch component {
        case .nanosecond:
            let allowedRange = Calendar.current.range(of: .nanosecond, in: .second, for: self)!
            guard allowedRange.contains(value) else { return nil }
            let currentNanoseconds = Calendar.current.component(.nanosecond, from: self)
            let nanosecondsToAdd = value - currentNanoseconds
            return Calendar.current.date(byAdding: .nanosecond, value: nanosecondsToAdd, to: self)
    
        case .second:
            let allowedRange = Calendar.current.range(of: .second, in: .minute, for: self)!
            guard allowedRange.contains(value) else { return nil }
            let currentSeconds = Calendar.current.component(.second, from: self)
            let secondsToAdd = value - currentSeconds
            return Calendar.current.date(byAdding: .second, value: secondsToAdd, to: self)
    
        case .minute:
            let allowedRange = Calendar.current.range(of: .minute, in: .hour, for: self)!
            guard allowedRange.contains(value) else { return nil }
            let currentMinutes = Calendar.current.component(.minute, from: self)
            let minutesToAdd = value - currentMinutes
            return Calendar.current.date(byAdding: .minute, value: minutesToAdd, to: self)
    
        case .hour:
            let allowedRange = Calendar.current.range(of: .hour, in: .day, for: self)!
            guard allowedRange.contains(value) else { return nil }
            let currentHour = Calendar.current.component(.hour, from: self)
            let hoursToAdd = value - currentHour
            return Calendar.current.date(byAdding: .hour, value: hoursToAdd, to: self)
    
        case .day:
            let allowedRange = Calendar.current.range(of: .day, in: .month, for: self)!
            guard allowedRange.contains(value) else { return nil }
            let currentDay = Calendar.current.component(.day, from: self)
            let daysToAdd = value - currentDay
            return Calendar.current.date(byAdding: .day, value: daysToAdd, to: self)
    
        case .month:
            let allowedRange = Calendar.current.range(of: .month, in: .year, for: self)!
            guard allowedRange.contains(value) else { return nil }
            let currentMonth = Calendar.current.component(.month, from: self)
            let monthsToAdd = value - currentMonth
            return Calendar.current.date(byAdding: .month, value: monthsToAdd, to: self)
    
        case .year:
            guard value > 0 else { return nil }
            let currentYear = Calendar.current.component(.year, from: self)
            let yearsToAdd = value - currentYear
            return Calendar.current.date(byAdding: .year, value: yearsToAdd, to: self)
    
        default:
            return Calendar.current.date(bySetting: component, value: value, of: self)
        }
    }
}

根据Calendar.Component获取最初时间

extension Date {
    ///
    ///     let date = Date() // "Jan 12, 2017, 7:14 PM"
    ///     let date2 = date.beginning(of: .hour) // "Jan 12, 2017, 7:00 PM"
    ///     let date3 = date.beginning(of: .month) // "Jan 1, 2017, 12:00 AM"
    ///     let date4 = date.beginning(of: .year) // "Jan 1, 2017, 12:00 AM"
    ///
    /// - Parameter component: calendar component to get date at the beginning of.
    /// - Returns: date at the beginning of calendar component (if applicable).
    public func beginning(of component: Calendar.Component) -> Date? {
        if component == .day {
            return Calendar.current.startOfDay(for: self)
        }
    
        var components: Set {
            switch component {
            case .second:
                return [.year, .month, .day, .hour, .minute, .second]
    
            case .minute:
                return [.year, .month, .day, .hour, .minute]
    
            case .hour:
                return [.year, .month, .day, .hour]
    
            case .weekOfYear, .weekOfMonth:
                return [.yearForWeekOfYear, .weekOfYear]
    
            case .month:
                return [.year, .month]
    
            case .year:
                return [.year]
    
            default:
                return []
            }
        }
    
        guard !components.isEmpty else { return nil }
        return Calendar.current.date(from: Calendar.current.dateComponents(components, from: self))
    }
}

根据Calendar.Component获取最末时间

extension Date {
    ///
    ///     let date = Date() // "Jan 12, 2017, 7:27 PM"
    ///     let date2 = date.end(of: .day) // "Jan 12, 2017, 11:59 PM"
    ///     let date3 = date.end(of: .month) // "Jan 31, 2017, 11:59 PM"
    ///     let date4 = date.end(of: .year) // "Dec 31, 2017, 11:59 PM"
    ///
    /// - Parameter component: calendar component to get date at the end of.
    /// - Returns: date at the end of calendar component (if applicable).
    public func end(of component: Calendar.Component) -> Date? {
        switch component {
        case .second:
            var date = adding(.second, value: 1)
            date = Calendar.current.date(from:
                Calendar.current.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date))!
            date.add(.second, value: -1)
            return date
    
        case .minute:
            var date = adding(.minute, value: 1)
            let after = Calendar.current.date(from:
                Calendar.current.dateComponents([.year, .month, .day, .hour, .minute], from: date))!
            date = after.adding(.second, value: -1)
            return date
    
        case .hour:
            var date = adding(.hour, value: 1)
            let after = Calendar.current.date(from:
                Calendar.current.dateComponents([.year, .month, .day, .hour], from: date))!
            date = after.adding(.second, value: -1)
            return date
    
        case .day:
            var date = adding(.day, value: 1)
            date = Calendar.current.startOfDay(for: date)
            date.add(.second, value: -1)
            return date
    
        case .weekOfYear, .weekOfMonth:
            var date = self
            let beginningOfWeek = Calendar.current.date(from:
                Calendar.current.dateComponents([.yearForWeekOfYear, .weekOfYear], from: date))!
            date = beginningOfWeek.adding(.day, value: 7).adding(.second, value: -1)
            return date
    
        case .month:
            var date = adding(.month, value: 1)
            let after = Calendar.current.date(from:
                Calendar.current.dateComponents([.year, .month], from: date))!
            date = after.adding(.second, value: -1)
            return date
    
        case .year:
            var date = adding(.year, value: 1)
            let after = Calendar.current.date(from:
                Calendar.current.dateComponents([.year], from: date))!
            date = after.adding(.second, value: -1)
            return date
    
        default:
            return nil
        }
    }
}

判断某个时间是否在给定的Calendar.Component内

extension Date {
    ///
    ///     Date().isInCurrent(.day) -> true
    ///     Date().isInCurrent(.year) -> true
    ///
    /// - Parameter component: calendar component to check.
    /// - Returns: true if date is in current given calendar component.
    public func isInCurrent(_ component: Calendar.Component) -> Bool {
        return Calendar.current.isDate(self, equalTo: Date(), toGranularity: component)
    }
}

日期按照给定的格式转化为日期字符串

extension Date {
    ///
    ///     Date().string(withFormat: "dd/MM/yyyy") -> "1/12/17"
    ///     Date().string(withFormat: "HH:mm") -> "23:50"
    ///     Date().string(withFormat: "dd/MM/yyyy HH:mm") -> "1/12/17 23:50"
    ///
    /// - Parameter format: Date format (default is "dd/MM/yyyy").
    /// - Returns: date string.
    public func string(withFormat format: String = "dd/MM/yyyy HH:mm") -> String {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = format
        return dateFormatter.string(from: self)
    }
}

根据格式样式转化为日期字符串

extension Date {
    ///
    ///     Date().dateString(ofStyle: .short) -> "1/12/17"
    ///     Date().dateString(ofStyle: .medium) -> "Jan 12, 2017"
    ///     Date().dateString(ofStyle: .long) -> "January 12, 2017"
    ///     Date().dateString(ofStyle: .full) -> "Thursday, January 12, 2017"
    ///
    /// - Parameter style: DateFormatter style (default is .medium).
    /// - Returns: date string.
    public func dateString(ofStyle style: DateFormatter.Style = .medium) -> String {
        let dateFormatter = DateFormatter()
        dateFormatter.timeStyle = .none
        dateFormatter.dateStyle = style
        return dateFormatter.string(from: self)
    }
}

根据格式样式转化为日期时间字符串

extension Date {
    ///
    ///     Date().dateTimeString(ofStyle: .short) -> "1/12/17, 7:32 PM"
    ///     Date().dateTimeString(ofStyle: .medium) -> "Jan 12, 2017, 7:32:00 PM"
    ///     Date().dateTimeString(ofStyle: .long) -> "January 12, 2017 at 7:32:00 PM GMT+3"
    ///     Date().dateTimeString(ofStyle: .full) -> "Thursday, January 12, 2017 at 7:32:00 PM GMT+03:00"
    ///
    /// - Parameter style: DateFormatter style (default is .medium).
    /// - Returns: date and time string.
    public func dateTimeString(ofStyle style: DateFormatter.Style = .medium) -> String {
        let dateFormatter = DateFormatter()
        dateFormatter.timeStyle = style
        dateFormatter.dateStyle = style
        return dateFormatter.string(from: self)
    }
}

根据格式样式转化为时间字符串

extension Date {
    ///
    ///     Date().timeString(ofStyle: .short) -> "7:37 PM"
    ///     Date().timeString(ofStyle: .medium) -> "7:37:02 PM"
    ///     Date().timeString(ofStyle: .long) -> "7:37:02 PM GMT+3"
    ///     Date().timeString(ofStyle: .full) -> "7:37:02 PM GMT+03:00"
    ///
    /// - Parameter style: DateFormatter style (default is .medium).
    /// - Returns: time string.
    public func timeString(ofStyle style: DateFormatter.Style = .medium) -> String {
        let dateFormatter = DateFormatter()
        dateFormatter.timeStyle = style
        dateFormatter.dateStyle = .none
        return dateFormatter.string(from: self)
    }
}

获取天(周名称)

extension Date {
    ///
    ///     Date().dayName(ofStyle: .oneLetter) -> "T"
    ///     Date().dayName(ofStyle: .threeLetters) -> "Thu"
    ///     Date().dayName(ofStyle: .full) -> "Thursday"
    ///
    /// - Parameter Style: style of day name (default is DayNameStyle.full).
    /// - Returns: day name string (example: W, Wed, Wednesday).
    public func dayName(ofStyle style: DayNameStyle = .full) -> String {
        // http://www.codingexplorer.com/swiftly-getting-human-readable-date-nsdateformatter/
        let dateFormatter = DateFormatter()
        var format: String {
            switch style {
            case .oneLetter:
                return "EEEEE"
            case .threeLetters:
                return "EEE"
            case .full:
                return "EEEE"
            }
        }
        dateFormatter.setLocalizedDateFormatFromTemplate(format)
        return dateFormatter.string(from: self)
    }
}

获取月

extension Date {
    ///
    ///     Date().monthName(ofStyle: .oneLetter) -> "J"
    ///     Date().monthName(ofStyle: .threeLetters) -> "Jan"
    ///     Date().monthName(ofStyle: .full) -> "January"
    ///
    /// - Parameter Style: style of month name (default is MonthNameStyle.full).
    /// - Returns: month name string (example: D, Dec, December).
    public func monthName(ofStyle style: MonthNameStyle = .full) -> String {
        // http://www.codingexplorer.com/swiftly-getting-human-readable-date-nsdateformatter/
        let dateFormatter = DateFormatter()
        var format: String {
            switch style {
            case .oneLetter:
                return "MMMMM"
            case .threeLetters:
                return "MMM"
            case .full:
                return "MMMM"
            }
        }
        dateFormatter.setLocalizedDateFormatFromTemplate(format)
        return dateFormatter.string(from: self)
    }
}

获取两个时间的秒数

extension Date {
    public func secondsSince(_ date: Date) -> Double {
        return timeIntervalSince(date)
    }
}

获取两个时间的分钟数

extension Date {
    public func minutesSince(_ date: Date) -> Double {
        return timeIntervalSince(date)/60
    }
}

获取两个时间的小时数

extension Date {
    public func hoursSince(_ date: Date) -> Double {
        return timeIntervalSince(date)/3600
    }
}

获取两个时间的天数

extension Date {
    public func daysSince(_ date: Date) -> Double {
        return timeIntervalSince(date)/(3600*24)
    }
}

检查某个时间是否在某个时间段内

extension Date {
    public func isBetween(_ startDate: Date, _ endDate: Date, includeBounds: Bool = false) -> Bool {
        if includeBounds {
            return startDate.compare(self).rawValue * compare(endDate).rawValue >= 0
        }
        return startDate.compare(self).rawValue * compare(endDate).rawValue > 0
    }
}

随机日期

extension Date {
    public static func random(from fromDate: Date = Date.distantPast, upTo toDate: Date = Date.distantFuture) -> Date {
        guard fromDate != toDate else {
            return fromDate
        }
    
        let diff = llabs(Int64(toDate.timeIntervalSinceReferenceDate - fromDate.timeIntervalSinceReferenceDate))
        var randomValue: Int64 = 0
        arc4random_buf(&randomValue, MemoryLayout.size)
        randomValue = llabs(randomValue%diff)
    
        let startReferenceDate = toDate > fromDate ? fromDate : toDate
        return startReferenceDate.addingTimeInterval(TimeInterval(randomValue))
    }
}

初始化

extension Date {
    ///
    ///     let date = Date(year: 2010, month: 1, day: 12) // "Jan 12, 2010, 7:45 PM"
    ///
    /// - Parameters:
    ///   - calendar: Calendar (default is current).
    ///   - timeZone: TimeZone (default is current).
    ///   - era: Era (default is current era).
    ///   - year: Year (default is current year).
    ///   - month: Month (default is current month).
    ///   - day: Day (default is today).
    ///   - hour: Hour (default is current hour).
    ///   - minute: Minute (default is current minute).
    ///   - second: Second (default is current second).
    ///   - nanosecond: Nanosecond (default is current nanosecond).
    public init?(
        calendar: Calendar? = Calendar.current,
        timeZone: TimeZone? = TimeZone.current,
        era: Int? = Date().era,
        year: Int? = Date().year,
        month: Int? = Date().month,
        day: Int? = Date().day,
        hour: Int? = Date().hour,
        minute: Int? = Date().minute,
        second: Int? = Date().second,
        nanosecond: Int? = Date().nanosecond) {
    
        var components = DateComponents()
        components.calendar = calendar
        components.timeZone = timeZone
        components.era = era
        components.year = year
        components.month = month
        components.day = day
        components.hour = hour
        components.minute = minute
        components.second = second
        components.nanosecond = nanosecond
    
        if let date = calendar?.date(from: components) {
            self = date
        } else {
            return nil
        }
    }
}

根据ISO8601字符串创建日期

extension Date {
    ///
    ///     let date = Date(iso8601String: "2017-01-12T16:48:00.959Z") // "Jan 12, 2017, 7:48 PM"
    ///
    /// - Parameter iso8601String: ISO8601 string of format (yyyy-MM-dd'T'HH:mm:ss.SSSZ).
    public init?(iso8601String: String) {
        // https://github.com/justinmakaila/NSDate-ISO-8601/blob/master/NSDateISO8601.swift
        let dateFormatter = DateFormatter()
        dateFormatter.locale = Locale(identifier: "en_US_POSIX")
        dateFormatter.timeZone = TimeZone.current
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
        if let date = dateFormatter.date(from: iso8601String) {
            self = date
        } else {
            return nil
        }
    }
}

根据时间戳创建日期

extension Date {
    ///
    ///     let date = Date(unixTimestamp: 1484239783.922743) // "Jan 12, 2017, 7:49 PM"
    ///
    /// - Parameter unixTimestamp: UNIX timestamp.
    public init(unixTimestamp: Double) {
        self.init(timeIntervalSince1970: unixTimestamp)
    }
}

根据整数创建日期

extension Date {
    ///
    ///     let date = Date(integerLiteral: 2017_12_25) // "2017-12-25 00:00:00 +0000"
    /// - Parameter value: Int value, e.g. 20171225, or 2017_12_25 etc.
    public init?(integerLiteral value: Int) {
        let formatter = DateFormatter()
        formatter.dateFormat = "yyyyMMdd"
        guard let date = formatter.date(from: String(value)) else { return nil }
        self = date
    }
}

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