swift 本月的第一天和最后一天
first and last day of the current month in swift
我正在尝试获取 swift 中该月的第一天和最后一天。
到目前为止我有以下内容：
let dateFormatter = NSDateFormatter()
let date = NSDate()
dateFormatter.dateFormat = "yyyy-MM-dd"
let calendar = NSCalendar.currentCalendar()
let components = calendar.components([.Year, .Month, .Day, .Hour, .Minute, .Second], fromDate: date)
let month = components.month
let year = components.year
let startOfMonth = ("\(year)-\(month)-01")
但我不确定如何获取最后日期。有没有我缺少的内置方法？显然它必须考虑到闰年等。
您只需使用
即可获得该月的第一天
let components = calendar.components([.Year, .Month], fromDate: date)
let startOfMonth = calendar.dateFromComponents(components)!
print(dateFormatter.stringFromDate(startOfMonth)) // 2015-11-01
要得到该月的最后一天，加一月减一日：
let comps2 = NSDateComponents()
comps2.month = 1
comps2.day = -1
let endOfMonth = calendar.dateByAddingComponents(comps2, toDate: startOfMonth, options: [])!
print(dateFormatter.stringFromDate(endOfMonth)) // 2015-11-30
或者，使用 rangeOfUnit 方法给你
月份的开始和长度：
var startOfMonth : NSDate?
var lengthOfMonth : NSTimeInterval = 0
calendar.rangeOfUnit(.Month, startDate: &startOfMonth, interval: &lengthOfMonth, forDate: date)
对于月份最后一天的日期，加上月份的长度减去一秒：
let endOfMonth = startOfMonth!.dateByAddingTimeInterval(lengthOfMonth - 1)
已针对 Swift5 更新：
extension Date {
var startOfDay: Date {
return Calendar.current.startOfDay(for: self)
}
var startOfMonth: Date {
let calendar = Calendar(identifier: .gregorian)
let components = calendar.dateComponents([.year, .month], from: self)
return calendar.date(from: components)!
}
var endOfDay: Date {
var components = DateComponents()
components.day = 1
components.second = -1
return Calendar.current.date(byAdding: components, to: startOfDay)!
}
var endOfMonth: Date {
var components = DateComponents()
components.month = 1
components.second = -1
return Calendar(identifier: .gregorian).date(byAdding: components, to: startOfMonth)!
}
func isMonday() -> Bool {
let calendar = Calendar(identifier: .gregorian)
let components = calendar.dateComponents([.weekday], from: self)
return components.weekday == 2
}
}
Swift 3 和 4 drop-in 分机
使用 Swift 3+:
这实际上变得 很多
- 你可以在没有守卫的情况下做到这一点（如果你想的话你可以，但是因为
DateComponents 现在是 non-optional 类型，所以不再需要它）。
- 使用 iOS 8 的
startOfDayForDate（现在是 startOfDay），您不需要手动将时间设置为中午 12 点，除非您正在跨时间进行一些非常疯狂的日历计算区域。
值得一提的是，其他一些答案声称您可以使用 Calendar.current.date(byAdding: .month, value: 0, to: Date())! 来简化此操作，但失败的地方在于它实际上并没有将当天归零，或者考虑了时区差异.
给你：
extension Date {
func startOfMonth() -> Date {
return Calendar.current.date(from: Calendar.current.dateComponents([.year, .month], from: Calendar.current.startOfDay(for: self)))!
}
func endOfMonth() -> Date {
return Calendar.current.date(byAdding: DateComponents(month: 1, day: -1), to: self.startOfMonth())!
}
}
print(Date().startOfMonth()) // "2018-02-01 08:00:00 +0000\n"
print(Date().endOfMonth()) // "2018-02-28 08:00:00 +0000\n"
使用Swift 3，您可以选择以下两种模式之一来检索一个月的第一天和最后一天。
#1。使用 Calendar dateComponents(_:from:), date(from:) and date(byAdding:to:wrappingComponents:) 方法
使用此模式，您首先获取一个月的第一天的日期，然后添加一个月并从中删除一天以获得该月最后一天的日期。下面的 Playground 代码显示了如何设置它：
import Foundation
// Set calendar and date
let calendar = Calendar.current
let date = calendar.date(byAdding: DateComponents(day: -10), to: Date())!
// Get first day of month
let firstDayComponents = calendar.dateComponents([.year, .month], from: date)
let firstDay = calendar.date(from: firstDayComponents)!
// Get last day of month
let lastDayComponents = DateComponents(month: 1, day: -1)
let lastDay = calendar.date(byAdding: lastDayComponents, to: firstDay)!
// Set date formatter
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_UK")
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .long
// Print results
print(dateFormatter.string(from: date)) // Prints: 22 March 2017 at 18:07:15 CET
print(dateFormatter.string(from: firstDay)) // Prints: 1 March 2017 at 00:00:00 CET
print(dateFormatter.string(from: lastDay)) // Prints: 31 March 2017 at 00:00:00 CEST
#2。使用 Calendar range(of:in:for:), dateComponents(_:from:) and date(from:) 和方法
使用此模式，您可以获得一个月中的绝对日期值范围，然后从中检索该月第一天和最后一天的日期。下面的 Playground 代码显示了如何设置它：
import Foundation
// Set calendar and date
let calendar = Calendar.current
let date = calendar.date(byAdding: DateComponents(day: -10), to: Date())!
// Get range of days in month
let range = calendar.range(of: .day, in: .month, for: date)! // Range(1..<32)
// Get first day of month
var firstDayComponents = calendar.dateComponents([.year, .month], from: date)
firstDayComponents.day = range.lowerBound
let firstDay = calendar.date(from: firstDayComponents)!
// Get last day of month
var lastDayComponents = calendar.dateComponents([.year, .month], from: date)
lastDayComponents.day = range.upperBound - 1
//lastDayComponents.day = range.count // also works
let lastDay = calendar.date(from: lastDayComponents)!
// Set date formatter
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_UK")
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .long
// Print results
print(dateFormatter.string(from: date)) // prints: 22 March 2017 at 18:07:15 CET
print(dateFormatter.string(from: firstDay)) // prints: 1 March 2017 at 00:00:00 CET
print(dateFormatter.string(from: lastDay)) // prints: 31 March 2017 at 00:00:00 CEST
使用 Swift 3 & iOS 10 我发现最简单的方法是 Calendar's dateInterval(of:for:):
guard let interval = calendar.dateInterval(of: .month, for: Date()) else { return }
然后您可以使用 interval.start 和 interval.end 来获取您需要的日期。
在swift3中，如果你把0放在day组件中，你可以得到这个月的最后一天。有一个示例代码：
public func isMoreDays(date: Date, asc: Bool)->Bool{
//components
var dayComponents = self.getDateComponents(date: date)
//asc is true if ascendant or false if descendant
dayComponents.day = asc ? 0 : 1
//plus 1 to month 'cos if you set up day to 0 you are going to the previous month
dayComponents.month = asc ? dayComponents.month! + 1 : dayComponents.month
//instantiate calendar and get the date
let calendar : Calendar = NSCalendar.current
let day = calendar.date(from: dayComponents)
//date comparison
if(day?.compare(date) == .orderedSame){
return false
}
return true
}
2017...
首先，获取您需要的月份：
let cal = Calendar.current
let d = Calendar.current.date(byAdding: .month, value: 0, to: Date())!
// for "last month" just use -1, for "next month" just use 1, etc
获取该月第一天是星期几：
let c = cal.dateComponents([.year, .month], from: d)
let FDOM = cal.date(from: c)!
let dowFDOM = cal.component(.weekday, from: FDOM)
print("the day-of-week on the 1st is ... \(dowFDOM)")
// so, that's 1=Sunday, 2=Monday, etc.
获取该月的天数：
let r = cal.range(of: .day, in: .month, for: d)!
let kDays = r.count
print("the number of days is ... \(kDays)")
Swift 3
许多日期示例：
Last 6 month,
last 3 month,
yesterday, last 7 day, last 30 day, previous month,
current month start & end, last month start & end date
let startDate = dateFormatter.string(from: Date().getThisMonthStart()!)
let endDate = dateFormatter.string(from: Date().getThisMonthEnd()!)
extension Date {
func getLast6Month() -> Date? {
return Calendar.current.date(byAdding: .month, value: -6, to: self)
}
func getLast3Month() -> Date? {
return Calendar.current.date(byAdding: .month, value: -3, to: self)
}
func getYesterday() -> Date? {
return Calendar.current.date(byAdding: .day, value: -1, to: self)
}
func getLast7Day() -> Date? {
return Calendar.current.date(byAdding: .day, value: -7, to: self)
}
func getLast30Day() -> Date? {
return Calendar.current.date(byAdding: .day, value: -30, to: self)
}
func getPreviousMonth() -> Date? {
return Calendar.current.date(byAdding: .month, value: -1, to: self)
}
// This Month Start
func getThisMonthStart() -> Date? {
let components = Calendar.current.dateComponents([.year, .month], from: self)
return Calendar.current.date(from: components)!
}
func getThisMonthEnd() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.month += 1
components.day = 1
components.day -= 1
return Calendar.current.date(from: components as DateComponents)!
}
//Last Month Start
func getLastMonthStart() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.month -= 1
return Calendar.current.date(from: components as DateComponents)!
}
//Last Month End
func getLastMonthEnd() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.day = 1
components.day -= 1
return Calendar.current.date(from: components as DateComponents)!
}
}
Swift 4
如果只需要序数日：
func lastDay(ofMonth m: Int, year y: Int) -> Int {
let cal = Calendar.current
var comps = DateComponents(calendar: cal, year: y, month: m)
comps.setValue(m + 1, for: .month)
comps.setValue(0, for: .day)
let date = cal.date(from: comps)!
return cal.component(.day, from: date)
}
lastDay(ofMonth: 2, year: 2018) // 28
lastDay(ofMonth: 2, year: 2020) // 29
这是最简单的解决方案：
extension Date {
func startOfMonth() -> Date {
let interval = Calendar.current.dateInterval(of: .month, for: self)
return (interval?.start.toLocalTime())! // Without toLocalTime it give last months last date
}
func endOfMonth() -> Date {
let interval = Calendar.current.dateInterval(of: .month, for: self)
return interval!.end
}
// Convert UTC (or GMT) to local time
func toLocalTime() -> Date {
let timezone = TimeZone.current
let seconds = TimeInterval(timezone.secondsFromGMT(for: self))
return Date(timeInterval: seconds, since: self)
}}
然后用你的日期实例调用它们：
print(Date().startOfMonth())
print(Date().endOfMonth())
这是我找到的最简单的方法 (Swift 5+):
extension Date {
func getStart(of component: Calendar.Component, calendar: Calendar = Calendar.current) -> Date? {
return calendar.dateInterval(of: component, for: self)?.start
}
func getEnd(of component: Calendar.Component, calendar: Calendar = Calendar.current) -> Date? {
return calendar.dateInterval(of: component, for: self)?.end
}
}
/**
Get last day of month..
*/
private func getLastDay(year:Int, month:Int) -> Int
{
var ret:Int = -1
switch month {
case 1:
ret = 31
break
case 2:
break
case 3:
ret = 31
break
case 4:
ret = 30
break
case 5:
ret = 31
break
case 6:
ret = 30
break
case 7:
ret = 31
break
case 8:
ret = 31
break
case 9:
ret = 30
break
case 10:
ret = 31
break
case 11:
ret = 30
break
case 12:
ret = 31
break
default:
print("bad num")
}
if(month == 2)
{
ret = 28
let t4 = year % 4
let l100 = year % 100
let l400 = year % 400
if(t4 == 0 && l100 != 0)
{
ret = 29
}
if(l400 == 0)
{
ret = 29
}
}
return ret
}
我正在尝试获取 swift 中该月的第一天和最后一天。
到目前为止我有以下内容：
let dateFormatter = NSDateFormatter()
let date = NSDate()
dateFormatter.dateFormat = "yyyy-MM-dd"
let calendar = NSCalendar.currentCalendar()
let components = calendar.components([.Year, .Month, .Day, .Hour, .Minute, .Second], fromDate: date)
let month = components.month
let year = components.year
let startOfMonth = ("\(year)-\(month)-01")
但我不确定如何获取最后日期。有没有我缺少的内置方法？显然它必须考虑到闰年等。
您只需使用
即可获得该月的第一天let components = calendar.components([.Year, .Month], fromDate: date)
let startOfMonth = calendar.dateFromComponents(components)!
print(dateFormatter.stringFromDate(startOfMonth)) // 2015-11-01
要得到该月的最后一天，加一月减一日：
let comps2 = NSDateComponents()
comps2.month = 1
comps2.day = -1
let endOfMonth = calendar.dateByAddingComponents(comps2, toDate: startOfMonth, options: [])!
print(dateFormatter.stringFromDate(endOfMonth)) // 2015-11-30
或者，使用 rangeOfUnit 方法给你
月份的开始和长度：
var startOfMonth : NSDate?
var lengthOfMonth : NSTimeInterval = 0
calendar.rangeOfUnit(.Month, startDate: &startOfMonth, interval: &lengthOfMonth, forDate: date)
对于月份最后一天的日期，加上月份的长度减去一秒：
let endOfMonth = startOfMonth!.dateByAddingTimeInterval(lengthOfMonth - 1)
已针对 Swift5 更新：
extension Date {
var startOfDay: Date {
return Calendar.current.startOfDay(for: self)
}
var startOfMonth: Date {
let calendar = Calendar(identifier: .gregorian)
let components = calendar.dateComponents([.year, .month], from: self)
return calendar.date(from: components)!
}
var endOfDay: Date {
var components = DateComponents()
components.day = 1
components.second = -1
return Calendar.current.date(byAdding: components, to: startOfDay)!
}
var endOfMonth: Date {
var components = DateComponents()
components.month = 1
components.second = -1
return Calendar(identifier: .gregorian).date(byAdding: components, to: startOfMonth)!
}
func isMonday() -> Bool {
let calendar = Calendar(identifier: .gregorian)
let components = calendar.dateComponents([.weekday], from: self)
return components.weekday == 2
}
}
Swift 3 和 4 drop-in 分机
使用 Swift 3+:
这实际上变得 很多- 你可以在没有守卫的情况下做到这一点（如果你想的话你可以，但是因为
DateComponents现在是 non-optional 类型，所以不再需要它）。 - 使用 iOS 8 的
startOfDayForDate（现在是startOfDay），您不需要手动将时间设置为中午 12 点，除非您正在跨时间进行一些非常疯狂的日历计算区域。
值得一提的是，其他一些答案声称您可以使用 Calendar.current.date(byAdding: .month, value: 0, to: Date())! 来简化此操作，但失败的地方在于它实际上并没有将当天归零，或者考虑了时区差异.
给你：
extension Date {
func startOfMonth() -> Date {
return Calendar.current.date(from: Calendar.current.dateComponents([.year, .month], from: Calendar.current.startOfDay(for: self)))!
}
func endOfMonth() -> Date {
return Calendar.current.date(byAdding: DateComponents(month: 1, day: -1), to: self.startOfMonth())!
}
}
print(Date().startOfMonth()) // "2018-02-01 08:00:00 +0000\n"
print(Date().endOfMonth()) // "2018-02-28 08:00:00 +0000\n"
使用Swift 3，您可以选择以下两种模式之一来检索一个月的第一天和最后一天。
#1。使用 Calendar dateComponents(_:from:), date(from:) and date(byAdding:to:wrappingComponents:) 方法
使用此模式，您首先获取一个月的第一天的日期，然后添加一个月并从中删除一天以获得该月最后一天的日期。下面的 Playground 代码显示了如何设置它：
import Foundation
// Set calendar and date
let calendar = Calendar.current
let date = calendar.date(byAdding: DateComponents(day: -10), to: Date())!
// Get first day of month
let firstDayComponents = calendar.dateComponents([.year, .month], from: date)
let firstDay = calendar.date(from: firstDayComponents)!
// Get last day of month
let lastDayComponents = DateComponents(month: 1, day: -1)
let lastDay = calendar.date(byAdding: lastDayComponents, to: firstDay)!
// Set date formatter
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_UK")
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .long
// Print results
print(dateFormatter.string(from: date)) // Prints: 22 March 2017 at 18:07:15 CET
print(dateFormatter.string(from: firstDay)) // Prints: 1 March 2017 at 00:00:00 CET
print(dateFormatter.string(from: lastDay)) // Prints: 31 March 2017 at 00:00:00 CEST
#2。使用 Calendar range(of:in:for:), dateComponents(_:from:) and date(from:) 和方法
使用此模式，您可以获得一个月中的绝对日期值范围，然后从中检索该月第一天和最后一天的日期。下面的 Playground 代码显示了如何设置它：
import Foundation
// Set calendar and date
let calendar = Calendar.current
let date = calendar.date(byAdding: DateComponents(day: -10), to: Date())!
// Get range of days in month
let range = calendar.range(of: .day, in: .month, for: date)! // Range(1..<32)
// Get first day of month
var firstDayComponents = calendar.dateComponents([.year, .month], from: date)
firstDayComponents.day = range.lowerBound
let firstDay = calendar.date(from: firstDayComponents)!
// Get last day of month
var lastDayComponents = calendar.dateComponents([.year, .month], from: date)
lastDayComponents.day = range.upperBound - 1
//lastDayComponents.day = range.count // also works
let lastDay = calendar.date(from: lastDayComponents)!
// Set date formatter
let dateFormatter = DateFormatter()
dateFormatter.locale = Locale(identifier: "en_UK")
dateFormatter.dateStyle = .long
dateFormatter.timeStyle = .long
// Print results
print(dateFormatter.string(from: date)) // prints: 22 March 2017 at 18:07:15 CET
print(dateFormatter.string(from: firstDay)) // prints: 1 March 2017 at 00:00:00 CET
print(dateFormatter.string(from: lastDay)) // prints: 31 March 2017 at 00:00:00 CEST
使用 Swift 3 & iOS 10 我发现最简单的方法是 Calendar's dateInterval(of:for:):
guard let interval = calendar.dateInterval(of: .month, for: Date()) else { return }
然后您可以使用 interval.start 和 interval.end 来获取您需要的日期。
在swift3中，如果你把0放在day组件中，你可以得到这个月的最后一天。有一个示例代码：
public func isMoreDays(date: Date, asc: Bool)->Bool{
//components
var dayComponents = self.getDateComponents(date: date)
//asc is true if ascendant or false if descendant
dayComponents.day = asc ? 0 : 1
//plus 1 to month 'cos if you set up day to 0 you are going to the previous month
dayComponents.month = asc ? dayComponents.month! + 1 : dayComponents.month
//instantiate calendar and get the date
let calendar : Calendar = NSCalendar.current
let day = calendar.date(from: dayComponents)
//date comparison
if(day?.compare(date) == .orderedSame){
return false
}
return true
}
2017...
首先，获取您需要的月份：
let cal = Calendar.current
let d = Calendar.current.date(byAdding: .month, value: 0, to: Date())!
// for "last month" just use -1, for "next month" just use 1, etc
获取该月第一天是星期几：
let c = cal.dateComponents([.year, .month], from: d)
let FDOM = cal.date(from: c)!
let dowFDOM = cal.component(.weekday, from: FDOM)
print("the day-of-week on the 1st is ... \(dowFDOM)")
// so, that's 1=Sunday, 2=Monday, etc.
获取该月的天数：
let r = cal.range(of: .day, in: .month, for: d)!
let kDays = r.count
print("the number of days is ... \(kDays)")
Swift 3
许多日期示例：
Last 6 month, last 3 month, yesterday, last 7 day, last 30 day, previous month, current month start & end, last month start & end date
let startDate = dateFormatter.string(from: Date().getThisMonthStart()!)
let endDate = dateFormatter.string(from: Date().getThisMonthEnd()!)
extension Date {
func getLast6Month() -> Date? {
return Calendar.current.date(byAdding: .month, value: -6, to: self)
}
func getLast3Month() -> Date? {
return Calendar.current.date(byAdding: .month, value: -3, to: self)
}
func getYesterday() -> Date? {
return Calendar.current.date(byAdding: .day, value: -1, to: self)
}
func getLast7Day() -> Date? {
return Calendar.current.date(byAdding: .day, value: -7, to: self)
}
func getLast30Day() -> Date? {
return Calendar.current.date(byAdding: .day, value: -30, to: self)
}
func getPreviousMonth() -> Date? {
return Calendar.current.date(byAdding: .month, value: -1, to: self)
}
// This Month Start
func getThisMonthStart() -> Date? {
let components = Calendar.current.dateComponents([.year, .month], from: self)
return Calendar.current.date(from: components)!
}
func getThisMonthEnd() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.month += 1
components.day = 1
components.day -= 1
return Calendar.current.date(from: components as DateComponents)!
}
//Last Month Start
func getLastMonthStart() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.month -= 1
return Calendar.current.date(from: components as DateComponents)!
}
//Last Month End
func getLastMonthEnd() -> Date? {
let components:NSDateComponents = Calendar.current.dateComponents([.year, .month], from: self) as NSDateComponents
components.day = 1
components.day -= 1
return Calendar.current.date(from: components as DateComponents)!
}
}
Swift 4
如果只需要序数日：
func lastDay(ofMonth m: Int, year y: Int) -> Int {
let cal = Calendar.current
var comps = DateComponents(calendar: cal, year: y, month: m)
comps.setValue(m + 1, for: .month)
comps.setValue(0, for: .day)
let date = cal.date(from: comps)!
return cal.component(.day, from: date)
}
lastDay(ofMonth: 2, year: 2018) // 28
lastDay(ofMonth: 2, year: 2020) // 29
这是最简单的解决方案：
extension Date {
func startOfMonth() -> Date {
let interval = Calendar.current.dateInterval(of: .month, for: self)
return (interval?.start.toLocalTime())! // Without toLocalTime it give last months last date
}
func endOfMonth() -> Date {
let interval = Calendar.current.dateInterval(of: .month, for: self)
return interval!.end
}
// Convert UTC (or GMT) to local time
func toLocalTime() -> Date {
let timezone = TimeZone.current
let seconds = TimeInterval(timezone.secondsFromGMT(for: self))
return Date(timeInterval: seconds, since: self)
}}
然后用你的日期实例调用它们：
print(Date().startOfMonth())
print(Date().endOfMonth())
这是我找到的最简单的方法 (Swift 5+):
extension Date {
func getStart(of component: Calendar.Component, calendar: Calendar = Calendar.current) -> Date? {
return calendar.dateInterval(of: component, for: self)?.start
}
func getEnd(of component: Calendar.Component, calendar: Calendar = Calendar.current) -> Date? {
return calendar.dateInterval(of: component, for: self)?.end
}
}
/**
Get last day of month..
*/
private func getLastDay(year:Int, month:Int) -> Int
{
var ret:Int = -1
switch month {
case 1:
ret = 31
break
case 2:
break
case 3:
ret = 31
break
case 4:
ret = 30
break
case 5:
ret = 31
break
case 6:
ret = 30
break
case 7:
ret = 31
break
case 8:
ret = 31
break
case 9:
ret = 30
break
case 10:
ret = 31
break
case 11:
ret = 30
break
case 12:
ret = 31
break
default:
print("bad num")
}
if(month == 2)
{
ret = 28
let t4 = year % 4
let l100 = year % 100
let l400 = year % 400
if(t4 == 0 && l100 != 0)
{
ret = 29
}
if(l400 == 0)
{
ret = 29
}
}
return ret
}