Ios 如何确定NSDate是否为今天?
如何检查Ios 如何确定NSDate是否为今天?,ios,objective-c,cocoa-touch,nsdate,nscalendar,Ios,Objective C,Cocoa Touch,Nsdate,Nscalendar,如何检查NSDate是否属于今天 我曾经用[aDate description]中的前10个字符检查它[[aDate description]substringToIndex:10]返回的字符串类似于“YYYY-MM-DD”,因此我将该字符串与[[NSDate-date]description]substringToIndex:10]返回的字符串进行了比较 是否有更快捷和/或简洁的检查方法 谢谢。您可以比较日期组件: NSDateComponents *otherDay = [[NSCalend
NSDate
是否属于今天
我曾经用[aDate description]
中的前10个字符检查它[[aDate description]substringToIndex:10]
返回的字符串类似于“YYYY-MM-DD”
,因此我将该字符串与[[NSDate-date]description]substringToIndex:10]
返回的字符串进行了比较
是否有更快捷和/或简洁的检查方法
谢谢。您可以比较日期组件:
NSDateComponents *otherDay = [[NSCalendar currentCalendar] components:NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay fromDate:aDate];
NSDateComponents *today = [[NSCalendar currentCalendar] components:NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay fromDate:[NSDate date]];
if([today day] == [otherDay day] &&
[today month] == [otherDay month] &&
[today year] == [otherDay year] &&
[today era] == [otherDay era]) {
//do stuff
}
编辑:
我更喜欢stefan的方法,我认为它有助于更清晰、更容易理解的if语句:
NSCalendar *cal = [NSCalendar currentCalendar];
NSDateComponents *components = [cal components:(NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:[NSDate date]];
NSDate *today = [cal dateFromComponents:components];
components = [cal components:(NSCalendarUnitEra | NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:aDate];
NSDate *otherDate = [cal dateFromComponents:components];
if([today isEqualToDate:otherDate]) {
//do stuff
}
克里斯,我采纳了你的建议。我必须查一下纪元是什么,所以对于其他不知道的人来说,它区分了公元前和公元后。这对大多数人来说可能是不必要的,但它很容易检查并增加了一些确定性,所以我把它包括在内。如果你想提高速度,这可能不是一个好方法
注意与许多答案一样,7年后,这完全过时了。在Swift中,现在只需使用
.isDateInToday
,您还可以检查您拥有的日期与当前日期之间的时间间隔:
[myDate timeIntervalSinceNow]
这将为您提供myDate和当前日期/时间之间的时间间隔(以秒为单位)
编辑:请大家注意:我很清楚,[myDate timeIntervalSinceNow]并不能明确地确定myDate是否在今天
我保留这个答案,这样如果有人在寻找类似的东西,并且[myDate TimeIntervalenceNow]很有用,他们可能会在这里找到它。我会尝试将今天的日期标准化为午夜,将第二个日期标准化为午夜,然后比较它是否是相同的NSDate 以下是将今天的日期正常化为午夜的方法,对第二个日期执行相同的操作并进行比较:
NSCalendar * gregorian = [[NSCalendar alloc]
initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents * components =
[gregorian components:
(NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit)
fromDate:[NSDate date]];
NSDate * today = [gregorian dateFromComponents:components];
这可能会被修改为NSDate类别,但我使用了:
// Seconds per day (24h * 60m * 60s)
#define kSecondsPerDay 86400.0f
+ (BOOL) dateIsToday:(NSDate*)dateToCheck
{
// Split today into components
NSCalendar* gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents* comps = [gregorian components:(NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit|NSHourCalendarUnit|NSMinuteCalendarUnit|NSSecondCalendarUnit)
fromDate:[NSDate date]];
// Set to this morning 00:00:00
[comps setHour:0];
[comps setMinute:0];
[comps setSecond:0];
NSDate* theMidnightHour = [gregorian dateFromComponents:comps];
[gregorian release];
// Get time difference (in seconds) between date and then
NSTimeInterval diff = [dateToCheck timeIntervalSinceDate:theMidnightHour];
return ( diff>=0.0f && diff<kSecondsPerDay );
}
//每天的秒数(24小时*60米*60秒)
#定义kSecondsPerDay 86400.0f
+(BOOL)dateIsToday:(NSDate*)dateToCheck
{
//今天分成几个部分
NSCalendar*gregorian=[[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents*comps=[公历成分:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit)
fromDate:[NSDate日期]];
//设置为今天早上00:00:00
[comps设置小时:0];
[comps setMinute:0];
[补偿设置秒:0];
NSDate*theMidnightHour=[GregorianDatefromComponents:comps];
[公历释放];
//获取日期和时间之间的时间差(以秒为单位)
NSTimeInterval diff=[dateToCheck timeIntervalSinceDate:TheMiddNightHour];
return(diff>=0.0f&&diff这是您的问题的一个分支,但是如果您想打印带有“今天”或“昨天”的NSDate,请使用该函数
- (void)setDoesRelativeDateFormatting:(BOOL)b
对于NSDateFormatter来说,如果您有很多这样的日期比较,那么对日历:组件:fromDate
的调用开始占用很多时间。根据我所做的一些分析,它们似乎相当昂贵
假设您正在尝试从一些日期数组中确定哪些日期(例如NSArray*datesToCompare
)与某个给定日期(例如NSDate*baseDate
)是同一天,那么您可以使用以下内容(部分改编自上面的答案):
我的解决方案是用除法计算自1970年以来经过了多少天,然后比较整数部分
#define kOneDay (60*60*24)
- (BOOL)isToday {
NSInteger offset = [[NSTimeZone defaultTimeZone] secondsFromGMT];
NSInteger days =[self timeIntervalSince1970] + offset;
NSInteger currentDays = [[NSDate date] timeIntervalSince1970] + offset;
return (days / kOneDay == currentDays / kOneDay);
}
请参阅苹果公司题为“执行日历计算”的文档条目
该页面上的清单13建议,要确定两天之间的午夜数,可以使用:
- (NSInteger)midnightsFromDate:(NSDate *)startDate toDate:(NSDate *)endDate
{
NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar];
NSInteger startDay = [calendar ordinalityOfUnit:NSDayCalendarUnit
inUnit:NSEraCalendarUnit
forDate:startDate];
NSInteger endDay = [calendar ordinalityOfUnit:NSDayCalendarUnit
inUnit:NSEraCalendarUnit
forDate:endDate];
return endDay - startDay;
}
然后,您可以使用该方法确定两天是否相同,并查看它是否返回0。无需处理组件、ERA和其他内容
NSCalendar提供了一种方法来获取现有日期的特定时间单位的开始
此代码将获取今天的开始日期和另一个日期,并将其进行比较。如果其计算结果为orsorderedsame
,则这两个日期都在同一天内-因此是今天
NSDate *today = nil;
NSDate *beginningOfOtherDate = nil;
NSDate *now = [NSDate date];
[[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&today interval:NULL forDate:now];
[[NSCalendar currentCalendar] rangeOfUnit:NSDayCalendarUnit startDate:&beginningOfOtherDate interval:NULL forDate:beginningOfOtherDate];
if([today compare:beginningOfOtherDate] == NSOrderedSame) {
//otherDate is a date in the current day
}
在macOS 10.9+和iOS 8+中,NSCalendar/Calendar上有一个方法可以做到这一点
- (BOOL)isDateInToday:(NSDate *)date
那你就这么做吧
目标-C:
BOOL today = [[NSCalendar currentCalendar] isDateInToday:date];
let today = Calendar.current.isDateInToday(date)
Swift 3:
BOOL today = [[NSCalendar currentCalendar] isDateInToday:date];
let today = Calendar.current.isDateInToday(date)
对于iOS7及更早版本:
//this is now => need that for the current date
NSDate * now = [NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[calendar setTimeZone:[NSTimeZone systemTimeZone]];
NSDateComponents * components = [calendar components:( NSYearCalendarUnit| NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit) fromDate: now];
[components setMinute:0];
[components setHour:0];
[components setSecond:0];
//this is Today's Midnight
NSDate *todaysMidnight = [calendar dateFromComponents: components];
//now timeIntervals since Midnight => in seconds
NSTimeInterval todayTimeInterval = [now timeIntervalSinceDate: todaysMidnight];
//now timeIntervals since OtherDate => in seconds
NSTimeInterval otherDateTimeInterval = [now timeIntervalSinceDate: otherDate];
if(otherDateTimeInterval > todayTimeInterval) //otherDate is not in today
{
if((otherDateTimeInterval - todayTimeInterval) <= 86400) //86400 == a day total seconds
{
@"yesterday";
}
else
{
@"earlier";
}
}
else
{
@"today";
}
now = nil;
calendar = nil;
components = nil;
todaysMidnight = nil;
NSLog("Thank you :-)");
//这是现在=>当前日期需要它吗
NSDate*现在=[NSDate日期];
NSCalendar*calendar=[[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];
[日历设置时区:[NSTimeZone systemTimeZone]];
NSDateComponents*components=[日历组件:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit)fromDate:now];
[组件设置分钟:0];
[组件设置小时:0];
[组件设置秒:0];
//今天是午夜
NSDate*todaysmitnight=[calendar dateFromComponents:components];
//现在,从午夜开始的时间间隔=>以秒为单位
NSTimeInterval todayTimeInterval=[现在的timeIntervalSinceDate:todaysMidnight];
//现在,从OtherDate开始的时间间隔=>以秒为单位
NSTimeInterval otherDateTimeInterval=[now TimeIntervalsIncestate:otherDate];
如果(otherDateTimeInterval>todayTimeInterval)//otherDate不在今天
{
如果((otherDateTimeInterval-todayTimeInterval)检查我们的Erica Sadun的很棒的NSDate扩展名
。使用非常简单。请在此处修改:
这篇文章已经有了:最佳答案的Swift版本:
let cal = NSCalendar.currentCalendar()
var components = cal.components([.Era, .Year, .Month, .Day], fromDate:NSDate())
let today = cal.dateFromComponents(components)!
components = cal.components([.Era, .Year, .Month, .Day], fromDate:aDate);
let otherDate = cal.dateFromComponents(components)!
if(today.isEqualToDate(otherDate)) {
//do stuff
}
这是我的2美分答案,基于公认的答案,但也支持更新的API。注意:我使用公历,因为大多数时间戳都是GMT,但如果您认为合适,请更改您的时间戳
func isDateToday(date: NSDate) -> Bool {
let calendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)!
if calendar.respondsToSelector("isDateInToday:") {
return calendar.isDateInToday(date)
}
let dateComponents = NSCalendarUnit.CalendarUnitYear | NSCalendarUnit.CalendarUnitMonth | NSCalendarUnit.CalendarUnitDay
let today = calendar.dateFromComponents(calendar.components(dateComponents, fromDate: NSDate()))!
let dateToCompare = calendar.dateFromComponents(calendar.components(dateComponents, fromDate: date))!
return dateToCompare == today
}
基于最佳答案的Swift扩展:
extension NSDate {
func isToday() -> Bool {
let cal = NSCalendar.currentCalendar()
if cal.respondsToSelector("isDateInToday:") {
return cal.isDateInToday(self)
}
var components = cal.components((.CalendarUnitEra | .CalendarUnitYear | .CalendarUnitMonth | .CalendarUnitDay), fromDate:NSDate())
let today = cal.dateFromComponents(components)!
components = cal.components((.CalendarUnitEra | .CalendarUnitYear | .CalendarUnitMonth | .CalendarUnitDay), fromDate:self);
let otherDate = cal.dateFromComponents(components)!
return today.isEqualToDate(otherDate)
}
}
在Swift 2.0上为我工作正确安全的解决方案,无需强制展开,在Swift 2.2和iOS 8之前工作:
func isToday() -> Bool {
let calendar = NSCalendar.currentCalendar()
if #available(iOS 8.0, *) {
return calendar.isDateInToday(self)
}
let todayComponents = calendar.components([.Era, .Year, .Month, .Day], fromDate:NSDate())
let dayComponents = calendar.components([.Era, .Year, .Month, .Day], fromDate:self)
guard let today = calendar.dateFromComponents(todayComponents),
day = calendar.dateFromComponents(dayComponents) else {
return false
}
return today.compare(day) == .OrderedSame
}
有一个e
extension NSDate {
func isToday() -> Bool {
let cal = NSCalendar.currentCalendar()
var components = cal.components([.Era, .Year, .Month, .Day], fromDate:NSDate())
let today = cal.dateFromComponents(components)!
components = cal.components([.Era, .Year, .Month, .Day], fromDate:self)
let otherDate = cal.dateFromComponents(components)!
return today.isEqualToDate(otherDate)
}
func isToday() -> Bool {
let calendar = NSCalendar.currentCalendar()
if #available(iOS 8.0, *) {
return calendar.isDateInToday(self)
}
let todayComponents = calendar.components([.Era, .Year, .Month, .Day], fromDate:NSDate())
let dayComponents = calendar.components([.Era, .Year, .Month, .Day], fromDate:self)
guard let today = calendar.dateFromComponents(todayComponents),
day = calendar.dateFromComponents(dayComponents) else {
return false
}
return today.compare(day) == .OrderedSame
}
NSDate *date = ... // The date you wish to test
NSCalendar *calendar = [NSCalendar currentCalendar];
if([calendar isDateInToday:date]) {
//do stuff
}
extension Date {
func isToday() -> Bool {
return Calendar.current.isDateInToday(self)
}
}