如何判断 NSDate 是否是今天?
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22-09-2019 - |
题
如何检查是否 NSDate
属于今天?
我曾经使用前 10 个字符来检查它 [aDate description]
. [[aDate description] substringToIndex:10]
返回类似字符串 "YYYY-MM-DD"
所以我将字符串与返回的字符串进行了比较 [[[NSDate date] description] substringToIndex:10]
.
有没有更快速和/或更简洁的方法来检查?
谢谢。
解决方案
在的MacOS 10.9+和iOS 8+,有上NSCalendar /那正是这样做的!
的方法日历- (BOOL)isDateInToday:(NSDate *)date
所以你根本就
<强>目标-C:强>
BOOL today = [[NSCalendar currentCalendar] isDateInToday:date];
<强>夫特3:强>
let today = Calendar.current.isDateInToday(date)
其他提示
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:
我喜欢Stefan的方法比较多,我觉得它使一个更清洁,更容易理解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,我已经纳入你的建议。我不得不寻找什么时代了,所以其他人谁不知道,这BC与AD区分。这可能是不必要的大多数人,但它很容易检查并增加了一些确定性,所以我已经包括了它。如果你要速度,这可能不是一个好方法呢。
注意强>作为与SO许多答案,经过7年,这是完全过时。在夫特现在只是使用.isDateInToday
这是一个分支你的问题,但如果你想打印一个NSDate与“今天”或“昨天”,使用功能
- (void)setDoesRelativeDateFormatting:(BOOL)b
有NSDateFormatter
我会尝试将今天的日期标准化为午夜,然后将第二个日期标准化为午夜,然后比较它是否是相同的 NSDate。
从 苹果的例子 以下是如何将今天的日期标准化为午夜,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];
工作的夫特3&4扩展按Catfish_Man的建议的:
extension Date {
func isToday() -> Bool {
return Calendar.current.isDateInToday(self)
}
}
没有必要与组件,时代和东西耍弄。
NSCalendar提供了一种方法来得到一定的时间单元的开始处为现有日期。
此代码将得到今天开始和另一个日期和比较。如果计算结果为NSOrderedSame
,首尾两天在同一天 - 所以今天
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
}
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)
}
为我工作于夫特2.0
夫特版本最佳答案的:
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
}
请参考苹果的文档录入题为“执行日历计算”的 [链接] 。
清单13在该网页上显示,来确定天之间的午夜数,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;
}
您可接着确定两个天都相同,通过使用该方法,看是否它返回0。
您还可以检查当前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)。
关联.
编辑:给大家注意:我很清楚 [myDate timeIntervalSinceNow] 并不能明确确定 myDate 是否是今天。
我保留这个答案,这样如果有人正在寻找类似的东西并且 [myDate timeIntervalSinceNow] 有用,他们可能会在这里找到它。
夫特扩展基于最佳答案:
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)
}
}
如果你有很多这些日期的比较,然后calendar:components:fromDate
调用start占用了大量的时间。根据一些剖析我已经做了,他们似乎是相当昂贵的。
说你是试图确定从日期,比如说NSArray *datesToCompare
的一些阵列,是在同一天某个给定的一天,说NSDate *baseDate
,那么你可以使用类似如下(从回答上述部分改编):
NSDate *baseDate = [NSDate date];
NSArray *datesToCompare = [NSArray arrayWithObjects:[NSDate date],
[NSDate dateWithTimeIntervalSinceNow:100],
[NSDate dateWithTimeIntervalSinceNow:1000],
[NSDate dateWithTimeIntervalSinceNow:-10000],
[NSDate dateWithTimeIntervalSinceNow:100000],
[NSDate dateWithTimeIntervalSinceNow:1000000],
[NSDate dateWithTimeIntervalSinceNow:50],
nil];
// determine the NSDate for midnight of the base date:
NSCalendar* calendar = [NSCalendar currentCalendar];
NSDateComponents* comps = [calendar components:(NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit)
fromDate:baseDate];
NSDate* theMidnightHour = [calendar dateFromComponents:comps];
// set up a localized date formatter so we can see the answers are right!
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateStyle:NSDateFormatterMediumStyle];
[dateFormatter setTimeStyle:NSDateFormatterMediumStyle];
// determine which dates in an array are on the same day as the base date:
for (NSDate *date in datesToCompare) {
NSTimeInterval interval = [date timeIntervalSinceDate:theMidnightHour];
if (interval >= 0 && interval < 60*60*24) {
NSLog(@"%@ is on the same day as %@", [dateFormatter stringFromDate:date], [dateFormatter stringFromDate:baseDate]);
}
else {
NSLog(@"%@ is NOT on the same day as %@", [dateFormatter stringFromDate:date], [dateFormatter stringFromDate:baseDate]);
}
}
输出:
Nov 23, 2011 1:32:00 PM is on the same day as Nov 23, 2011 1:32:00 PM
Nov 23, 2011 1:33:40 PM is on the same day as Nov 23, 2011 1:32:00 PM
Nov 23, 2011 1:48:40 PM is on the same day as Nov 23, 2011 1:32:00 PM
Nov 23, 2011 10:45:20 AM is on the same day as Nov 23, 2011 1:32:00 PM
Nov 24, 2011 5:18:40 PM is NOT on the same day as Nov 23, 2011 1:32:00 PM
Dec 5, 2011 3:18:40 AM is NOT on the same day as Nov 23, 2011 1:32:00 PM
Nov 23, 2011 1:32:50 PM is on the same day as Nov 23, 2011 1:32:00 PM
有比许多上述答案更简单的方法!
NSDate *date = ... // The date you wish to test
NSCalendar *calendar = [NSCalendar currentCalendar];
if([calendar isDateInToday:date]) {
//do stuff
}
这也许可以作为返工一个NSDate类别,但我用:
// 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 );
}
(然而,当比较的两个日期字符串作为在原来的问题几乎感觉“清洁器”。)
有iOS7和更早:
//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 :-)");
检查我们的埃里卡Sadun的伟大NSDate extension
。使用方法很简单。细在这里:
http://github.com/erica/NSDate-Extensions
它已经存在于这个帖子: https://stackoverflow.com/a/4052798/362310
不正确和安全的解决方案的力展开,上夫特2.2和前iOS 8的工作:
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
}
下面是上公认的答案,但支持较新的API,以及我的2%的答案建设。注:我使用的公历,因为大多数时间标记均为而改变你的,你认为合适
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
}
我的解决办法是计算由分割天自1970年以来多少传递和比较的整数部分
#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);
}
NSDate *dateOne = yourDate;
NSDate *dateTwo = [NSDate date];
switch ([dateOne compare:dateTwo])
{
case NSOrderedAscending:
NSLog(@”NSOrderedAscending”);
break;
case NSOrderedSame:
NSLog(@”NSOrderedSame”);
break;
case NSOrderedDescending:
NSLog(@”NSOrderedDescending”);
break;
}