如何判断 NSDate 是否是今天？

Question

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。

Answer 1

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：

BOOL today = [[NSCalendar currentCalendar] isDateInToday:date];

<强>夫特3：

let today = Calendar.current.isDateInToday(date)

Answer 2

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

Answer 3

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

Answer 4

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];

Answer 5

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)
    }

}

Answer 6

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
}

Answer 7

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

Answer 8

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
}

Answer 9

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。

Answer 10

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。

Answer 11

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)
    }
}

Answer 12

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

Answer 13

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
}

Answer 14

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”。）

Answer 15

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 :-)");

Answer 16

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

Answer 17

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
}

Answer 18

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
}

Answer 19

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);
}

Answer 20

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;  
}