我们在日历中有这些方便的功能:
let calendar = NSCalendar.currentCalendar()
calendar.isDateInToday(date)
calendar.isDateInTomorrow(date)
但我错过了那两个:
calendar.isDateInNextWeek(日期)
calendar.isDateInNextMonth(日期)
正如@Rob所提到的那样,意思是:"在本周日开始的日历周中,经过下一个星期六"
我很难确定如何以一种涵盖所有极端情况的强大方式实现这些功能。
有人可以提供助理吗?
答案 0 :(得分:4)
算法并不十分壮观:
NSCalendar为我们完成了大部分工作。但它看起来仍然有点令人生畏,至少如果你不经常使用这些日期方法。您应该阅读所有这些方法的文档以了解它们。
let calendar = NSCalendar.currentCalendar()
let date = NSDate()
var startOfThisWeek: NSDate?
if !calendar.rangeOfUnit(.CalendarUnitWeekOfMonth, startDate: &startOfThisWeek, interval: nil, forDate: date) {
fatalError("Can't calculate start of this week")
}
let startOfNextWeek = calendar.dateByAddingUnit(.CalendarUnitWeekOfMonth, value: 1, toDate: startOfThisWeek!, options: nil)!
let startOfNextNextWeek = calendar.dateByAddingUnit(.CalendarUnitWeekOfMonth, value: 1, toDate: startOfNextWeek, options: nil)!
只需使用.CalendarUnitWeekOfMonth
切换.CalendarUnitMonth
即可获得此次,下次和下个月的计算结果。
var startOfThisMonth: NSDate?
if !calendar.rangeOfUnit(.CalendarUnitMonth, startDate: &startOfThisMonth, interval: nil, forDate: date) {
fatalError("Can't calculate start of this month")
}
let startOfNextMonth = calendar.dateByAddingUnit(.CalendarUnitMonth, value: 1, toDate: startOfThisMonth!, options: nil)!
let startOfNextNextMonth = calendar.dateByAddingUnit(.CalendarUnitMonth, value: 1, toDate: startOfNextMonth, options: nil)!
测试:
let testDate = NSDate(timeIntervalSinceNow: 7*24*60*60)
if startOfThisWeek <= testDate && testDate < startOfNextWeek {
println("\(testDate) is this week")
}
if startOfNextWeek <= testDate && testDate < startOfNextNextWeek {
println("\(testDate) is next week")
}
if startOfThisMonth <= testDate && testDate < startOfNextMonth {
println("\(testDate) is this month")
}
if startOfNextMonth <= testDate && testDate < startOfNextNextMonth {
println("\(testDate) is next month")
}
结果:
“2015-03-22 02:55:19 +0000是下周” “2015-03-22 02:55:19 +0000是本月”
听起来不错。
如果您想使用<=
,==
,<
等而不是丑陋(并且令人困惑)NSComparisonResult
,您也需要这样做:
public func ==(lhs: NSDate, rhs: NSDate) -> Bool {
return lhs === rhs || lhs.compare(rhs) == .OrderedSame
}
public func <(lhs: NSDate, rhs: NSDate) -> Bool {
return lhs.compare(rhs) == .OrderedAscending
}
extension NSDate: Comparable { }
这是iOS8代码。如果要编写适用于旧版本的代码,则必须使用旧的NSDateComponents替换dateByAddingUnit:value::toDate:options:
。即:
let offSetComponents = NSDateComponents()
offSetComponents.weekOfMonth = 1
let startOfNextWeek = calendar.dateByAddingComponents(offSetComponents, toDate: startOfThisWeek, options: nil)
答案 1 :(得分:1)
使用Swift 5
解决了问题,并扩展了Calendar
。
extension Calendar {
private var currentDate: Date { return Date() }
func isDateInThisWeek(_ date: Date) -> Bool {
return isDate(date, equalTo: currentDate, toGranularity: .weekOfYear)
}
func isDateInThisMonth(_ date: Date) -> Bool {
return isDate(date, equalTo: currentDate, toGranularity: .month)
}
func isDateInNextWeek(_ date: Date) -> Bool {
guard let nextWeek = self.date(byAdding: DateComponents(weekOfYear: 1), to: currentDate) else {
return false
}
return isDate(date, equalTo: nextWeek, toGranularity: .weekOfYear)
}
func isDateInNextMonth(_ date: Date) -> Bool {
guard let nextMonth = self.date(byAdding: DateComponents(month: 1), to: currentDate) else {
return false
}
return isDate(date, equalTo: nextMonth, toGranularity: .month)
}
func isDateInFollowingMonth(_ date: Date) -> Bool {
guard let followingMonth = self.date(byAdding: DateComponents(month: 2), to: currentDate) else {
return false
}
return isDate(date, equalTo: followingMonth, toGranularity: .month)
}
}
用法:
let day: Double = 60 * 60 * 24
let currentDate = Date() // Thu 25 Apr 2019
let futureDate = Date(timeInterval: 3 * day, since: currentDate) // Sun 28 Apr 2019
if Calendar.current.isDateInThisWeek(futureDate) {
// this will be executed if first day of week is Monday
} else {
// this will be executed if first day of week is Sunday
}
代码根据Calendar
实例评估日期是否在范围内(sameWeek,nextWeek)。
如果Calendar
实例为current
,它将根据设备设置确定一周的开始时间(星期一或星期天),但是如果您想要其他行为,则可以更改Calendar
实例:
Calendar(identifier: .chinese).isDateInNextWeek(someDate)
如果我们尝试使用诸如DateComponents
之类的不正确值创建DateComponents(year: 2019, month: 13)
,则此代码也适用。
在这种情况下,它将创建日期01 Jan 2020
。
答案 2 :(得分:0)
我想出了这个天真的代码:
extension NSCalendar
{
func isDateInNextWeek(value: NSDate) -> Bool
{
let componentsValue = self.components(.WeekOfYearCalendarUnit | .YearCalendarUnit, fromDate: value)
let componentsToday = self.components(.WeekOfYearCalendarUnit | .YearCalendarUnit, fromDate: NSDate())
let weekOfYearValue = componentsValue.weekOfYear
let weekOfYearToday = componentsToday.weekOfYear
let yearValue = componentsValue.year
let yearToday = componentsToday.year
if(yearValue < yearToday)
{
return false
}
else if(yearValue == yearToday && weekOfYearValue - weekOfYearToday == 1)
{
return true
}
else if(yearValue - yearToday == 1 && weekOfYearValue == 1 && weekOfYearToday == 52)
{
return true
}
else
{
return false
}
}
}
但我必须在这里错过一些边缘案例。