objective-c - 如何在 Objective-C 中比较两个日期

Question

我有两个日期：2009-05-11和当前日期。我想检查给定日期是否是当前日期。这怎么可能。

Answer 1

Cocoa 有两种方法：

在 NSDate

– isEqualToDate:  
– earlierDate:  
– laterDate:  
– compare:

当您使用 时- (NSComparisonResult)compare:(NSDate *)anotherDate，您将获得以下其中一项：

The receiver and anotherDate are exactly equal to each other, NSOrderedSame
The receiver is later in time than anotherDate, NSOrderedDescending
The receiver is earlier in time than anotherDate, NSOrderedAscending.

例子：

NSDate * now = [NSDate date];
NSDate * mile = [[NSDate alloc] initWithString:@"2001-03-24 10:45:32 +0600"];
NSComparisonResult result = [now compare:mile];

NSLog(@"%@", now);
NSLog(@"%@", mile);

switch (result)
{
    case NSOrderedAscending: NSLog(@"%@ is in future from %@", mile, now); break;
    case NSOrderedDescending: NSLog(@"%@ is in past from %@", mile, now); break;
    case NSOrderedSame: NSLog(@"%@ is the same as %@", mile, now); break;
    default: NSLog(@"erorr dates %@, %@", mile, now); break;
}

[mile release];

Answer 2

在这里，伙计。此功能会将您的日期与任何特定日期匹配，并且能够判断它们是否匹配。您还可以修改组件以满足您的要求。

- (BOOL)isSameDay:(NSDate*)date1 otherDay:(NSDate*)date2 {
NSCalendar* calendar = [NSCalendar currentCalendar];

unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit;
NSDateComponents* comp1 = [calendar components:unitFlags fromDate:date1];
NSDateComponents* comp2 = [calendar components:unitFlags fromDate:date2];

return [comp1 day]   == [comp2 day] &&
[comp1 month] == [comp2 month] &&
[comp1 year]  == [comp2 year];}

问候， Naveed Butt

Answer 3

NSDate *today = [NSDate date]; // it will give you current date
NSDate *newDate = [NSDate dateWithString:@"xxxxxx"]; // your date 

NSComparisonResult result; 
//has three possible values: NSOrderedSame,NSOrderedDescending, NSOrderedAscending

result = [today compare:newDate]; // comparing two dates

if(result==NSOrderedAscending)
    NSLog(@"today is less");
else if(result==NSOrderedDescending)
    NSLog(@"newDate is less");
else
    NSLog(@"Both dates are same");

您可以使用其他方法来比较 NSDate 对象。每种方法在某些任务上都会更有效。我选择了 compare 方法，因为它可以处理您的大部分基本日期比较需求。

Answer 4

此类别提供了一种比较 NSDates 的简洁方法：

#import <Foundation/Foundation.h>

@interface NSDate (Compare)

-(BOOL) isLaterThanOrEqualTo:(NSDate*)date;
-(BOOL) isEarlierThanOrEqualTo:(NSDate*)date;
-(BOOL) isLaterThan:(NSDate*)date;
-(BOOL) isEarlierThan:(NSDate*)date;
//- (BOOL)isEqualToDate:(NSDate *)date; already part of the NSDate API

@end

和实施：

#import "NSDate+Compare.h"

@implementation NSDate (Compare)

-(BOOL) isLaterThanOrEqualTo:(NSDate*)date {
    return !([self compare:date] == NSOrderedAscending);
}

-(BOOL) isEarlierThanOrEqualTo:(NSDate*)date {
    return !([self compare:date] == NSOrderedDescending);
}
-(BOOL) isLaterThan:(NSDate*)date {
    return ([self compare:date] == NSOrderedDescending);

}
-(BOOL) isEarlierThan:(NSDate*)date {
    return ([self compare:date] == NSOrderedAscending);
}

@end

使用简单：

if([aDateYouWantToCompare isEarlierThanOrEqualTo:[NSDate date]]) // [NSDate date] is now
{
    // do your thing ...
}

Answer 5

如果您将两个日期都设为NSDates，则可以使用NSDate'compare:方法：

NSComparisonResult result = [Date2 compare:Date1];

if(result==NSOrderedAscending)
    NSLog(@"Date1 is in the future");
else if(result==NSOrderedDescending)
    NSLog(@"Date1 is in the past");
else
    NSLog(@"Both dates are the same");

您可以在此处查看文档。

Answer 6

通过这种方法，您也可以比较两个日期

NSDate * dateOne = [NSDate date];
NSDate * dateTwo = [NSDate date];

if([dateOne compare:dateTwo] == NSOrderedAscending)
{

}

Answer 7

我发现的最好方法是检查给定日期和今天之间的差异：

NSCalendar* calendar = [NSCalendar currentCalendar];
NSDate* now = [NSDate date];
int differenceInDays =
[calendar ordinalityOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitEra forDate:date] -
[calendar ordinalityOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitEra forDate:now];

根据Apple 的日期和时间编程指南[NSCalendar ordinalityOfUnit:NSDayCalendarUnit inUnit: NSEraCalendarUnit forDate:myDate] 中的日历计算清单 13为您提供了自时代开始以来的午夜数。这样可以很容易地检查日期是昨天、今天还是明天。

switch (differenceInDays) {
    case -1:
        dayString = @"Yesterday";
        break;
    case 0:
        dayString = @"Today";
        break;
    case 1:
        dayString = @"Tomorrow";
        break;
    default: {
        NSDateFormatter* dayFormatter = [[NSDateFormatter alloc] init];
        [dayFormatter setLocale:usLocale];
        [dayFormatter setDateFormat:@"dd MMM"];
        dayString = [dayFormatter stringFromDate: date];
        break;
    }
}

Answer 8

NSDateFormatter *df= [[NSDateFormatter alloc] init];

[df setDateFormat:@"yyyy-MM-dd"];

NSDate *dt1 = [[NSDate alloc] init];

NSDate *dt2 = [[NSDate alloc] init];

dt1=[df dateFromString:@"2011-02-25"];

dt2=[df dateFromString:@"2011-03-25"];

NSComparisonResult result = [dt1 compare:dt2];

switch (result)
{

        case NSOrderedAscending: NSLog(@"%@ is greater than %@", dt2, dt1); break;

        case NSOrderedDescending: NSLog(@"%@ is less %@", dt2, dt1); break;

        case NSOrderedSame: NSLog(@"%@ is equal to %@", dt2, dt1); break;

        default: NSLog(@"erorr dates %@, %@", dt2, dt1); break;

}

享受编码......

Answer 9

在 Cocoa 中，要比较日期，请在对象上使用、、 和方法之一isEqualToDate，并用您需要的日期进行实例化。comparelaterDateearlierDateNSDate

文档： http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDate_Class/Reference/Reference.html#//apple_ref/occ/instm/NSDate/isEqualToDate：
http:
//developer.apple。 com/documentation/Cocoa/Reference/Foundation/Classes/NSDate_Class/Reference/Reference.html#//apple_ref/occ/instm/NSDate/earlierDate：http:
//developer.apple.com/documentation/Cocoa/Reference/Foundation/类/NSDate_Class/Reference/Reference.html#//apple_ref/occ/instm/NSDate/laterDate：http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDate_Class/Reference/Reference.html#
//apple_ref/occ/instm/NSDate/比较：

Answer 10

您真正需要的是比较两个相同类型的对象。

1. 从您的字符串日期 (@"2009-05-11") 中创建一个 NSDate ：
   http://blog.evandavey.com/2008/12/how-to-convert-a-string-to-nsdate.html

2. 如果当前日期也是字符串，则将其设为 NSDate。如果它已经是 NSDate，请离开它。

Answer 11

这是 Pascal 答案的 Swift 变体：

extension NSDate {

    func isLaterThanOrEqualTo(date:NSDate) -> Bool {
        return !(self.compare(date) == NSComparisonResult.OrderedAscending)
    }

    func isEarlierThanOrEqualTo(date:NSDate) -> Bool {
        return !(self.compare(date) == NSComparisonResult.OrderedDescending)
    }

    func isLaterThan(date:NSDate) -> Bool {
        return (self.compare(date) == NSComparisonResult.OrderedDescending)
    }

    func isEarlierThan(date:NSDate) -> Bool {
        return (self.compare(date) == NSComparisonResult.OrderedAscending)
    }
}

可以用作：

self.expireDate.isEarlierThanOrEqualTo(NSDate())

Answer 12

如果其他人正在寻找它，这是从Naveed Rafi的答案转换为 Swift 的函数：

func isSameDate(#date1: NSDate, date2: NSDate) -> Bool {
    let calendar = NSCalendar()
    let date1comp = calendar.components(.YearCalendarUnit | .MonthCalendarUnit | .DayCalendarUnit, fromDate: date1)
    let date2comp = calendar.components(.YearCalendarUnit | .MonthCalendarUnit | .DayCalendarUnit, fromDate: date2)
    return (date1comp.year == date2comp.year) && (date1comp.month == date2comp.month) && (date1comp.day == date2comp.day)
}

Answer 13

Get Today's Date:

NSDate* date = [NSDate date];

Create a Date From Scratch:    
NSDateComponents* comps = [[NSDateComponents alloc]init];
comps.year = 2015;
comps.month = 12;
comps.day = 31;
NSCalendar* calendar = [NSCalendar currentCalendar];
NSDate* date = [calendar dateFromComponents:comps];


Add a day to a Date:  
NSDate* date = [NSDate date];
NSDateComponents* comps = [[NSDateComponents alloc]init];
comps.day = 1;
NSCalendar* calendar = [NSCalendar currentCalendar];
NSDate* tomorrow = [calendar dateByAddingComponents:comps toDate:date options:nil];


Subtract a day from a Date:    
NSDate* date = [NSDate date];
NSDateComponents* comps = [[NSDateComponents alloc]init];
comps.day = -1;
NSCalendar* calendar = [NSCalendar currentCalendar];
NSDate* yesterday = [calendar dateByAddingComponents:comps toDate:date options:nil];



Convert a Date to a String:  

NSDate* date = [NSDate date];
NSDateFormatter* formatter = [[NSDateFormatter alloc]init];
formatter.dateFormat = @"MMMM dd, yyyy";
NSString* dateString = [formatter stringFromDate:date];


Convert a String to a Date:

NSDateFormatter* formatter = [[NSDateFormatter alloc]init];
formatter.dateFormat = @"MMMM dd, yyyy";
NSDate* date = [formatter dateFromString:@"August 02, 2014"];


Find how many days are in a month:    
NSDate* date = [NSDate date];
NSCalendar* cal = [NSCalendar currentCalendar];
NSRange currentRange = [cal rangeOfUnit:NSDayCalendarUnit inUnit:NSMonthCalendarUnit forDate:date];
NSInteger numberOfDays = currentRange.length;


Calculate how much time something took:   

NSDate* start = [NSDate date];
for(int i = 0; i < 1000000000; i++);
NSDate* end = [NSDate date];
NSTimeInterval duration = [end timeIntervalSinceDate:start];


Find the Day Of Week for a specific Date:

NSDate* date = [NSDate date];
NSCalendar* cal = [NSCalendar currentCalendar];
NSInteger dow = [cal ordinalityOfUnit:NSWeekdayCalendarUnit inUnit:NSWeekCalendarUnit forDate:date];

然后使用 NSComparisonResult 比较日期。

Answer 14

..

NSString *date = @"2009-05-11"
NSString *nowDate = [[[NSDate date]description]substringToIndex: 10];
if([date isEqualToString: nowDate])
{
// your code
}