如何检查NSDate是否属于今天？
我曾经使用[aDate description]中的前10个字符进行检查。 [[aDate description] substringToIndex:10]返回"YYYY-MM-DD"之类的字符串，因此我将字符串与[[[NSDate date] description] substringToIndex:10]返回的字符串进行了比较。
有更快速和/或更好的方法来检查吗？
感谢。
答案 0 :(得分：294)
在macOS 10.9+＆amp; iOS 8+，NSCalendar / Calendar上的一种方法就是这样做的！
- (BOOL)isDateInToday:(NSDate *)date
所以你只需要做
<强>目标-C：
BOOL today = [[NSCalendar currentCalendar] isDateInToday:date];
斯威夫特3：
let today = Calendar.current.isDateInToday(date)
答案 1 :(得分：192)
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，我认为如果声明更清晰，更容易理解：
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
}
注意与SO上的许多答案一样，7年后这已经完全过时了。现在在Swift中使用.isDateInToday
答案 2 :(得分：27)
这是您的问题的分支，但如果您想要使用“今天”或“昨天”打印NSDate，请使用该功能
- (void)setDoesRelativeDateFormatting:(BOOL)b
表示NSDateFormatter
答案 3 :(得分：16)
我会尝试将今天的日期标准化为午夜和第二个日期，标准化为午夜，然后比较它是否是相同的NSDate。
从an Apple example这里是你如何规范化到今天午夜的日期，对第二个日期做同样的事情并进行比较：
NSCalendar * gregorian = [[NSCalendar alloc]
initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents * components =
[gregorian components:
(NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit)
fromDate:[NSDate date]];
NSDate * today = [gregorian dateFromComponents:components];
答案 4 :(得分：13)
工作 Swift 3＆amp; Catfish_Man建议的4个扩展：
extension Date {
func isToday() -> Bool {
return Calendar.current.isDateInToday(self)
}
}
答案 5 :(得分：12)
无需处理组件，时代和内容。
NSCalendar提供了一种方法来获取现有日期的特定时间单位的开头。
此代码将获取今天和另一个日期的开头并进行比较。如果评估为NSOrderedSame，则两个日期都在同一天 - 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
}
答案 6 :(得分：8)
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)
}
在Swift 2.0上为我工作
答案 7 :(得分：6)
Swift版本的最佳答案：
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
}
答案 8 :(得分：5)
请参阅Apple的文档条目“执行日历计算”[link]。
该页面上的清单13建议，要确定天数之间的中间夜数，请使用：
- (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，您可以通过使用该方法确定两天是否相同，并查看它是否返回0。
答案 9 :(得分：5)
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与当前日期/时间之间的时间间隔（以秒为单位）。
编辑：请注意每个人：我很清楚[myDate timeIntervalSinceNow]并没有明确地确定myDate是否是今天。
我将这样的答案保留下来，以便如果某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。
答案 10 :(得分：4)
基于最佳答案的Swift Extension：
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)
}
}
答案 11 :(得分：2)
如果你有很多这些日期比较，那么对calendar:components:fromDate的调用开始占用大量时间。根据我所做的一些分析，它们似乎相当昂贵。
假设您正在尝试确定某些日期中的哪一个，比如NSArray *datesToCompare，与某一天相同，比如NSDate *baseDate，那么您可以使用以下内容（部分改编）从上面的答案）：
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
答案 12 :(得分：2)
有一种比上述答案更容易的方法！
NSDate *date = ... // The date you wish to test
NSCalendar *calendar = [NSCalendar currentCalendar];
if([calendar isDateInToday:date]) {
//do stuff
}
答案 13 :(得分：0)
这可能会作为NSDate类别重新编写，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 );
}
（但是，比较原始问题中的两个日期字符串几乎感觉“更干净”..）
答案 14 :(得分：0)
适用于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 :-)");
答案 15 :(得分：0)
查看我们的Erica Sadun的精彩NSDate extension。使用非常简单。好在这里：
答案 16 :(得分：0)
没有强制解包的正确而安全的解决方案，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
}
答案 17 :(得分：-1)
这是我根据接受的答案建立的2分答案，但也支持更新的API。注意：我使用格里高利历，因为大多数时间戳都是格林尼治标准时间，但是你认为合适时会改变你的时间
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
}
答案 18 :(得分：-3)
我的解决方案是通过除法计算自1970年以来经过的天数并比较整数部分
#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);
}
答案 19 :(得分：-4)
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;
}