如何比较Objective-C中的两个date
我有两个date： 2009-05-11和当前date。 我想检查给定的date是否是当前date。 这怎么可能。
cocoa有几个方法 ：
在NSDate
– isEqualToDate: – earlierDate: – laterDate: – compare:
当你使用- (NSComparisonResult)compare:(NSDate *)anotherDate ，你会得到其中的一个：
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：
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];
这里哥们。 此function会将您的date与任何指定的date相匹配，并会告诉您天气是否匹配。 您还可以修改组件以符合您的要求。
- (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屁股
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");
还有其他的方法可以用来比较一个NSDate对象。 在某些任务中，每种方法都会更有效率。 我select了比较方法，因为它将处理大部分基本date比较需求。
这个类别提供了一个比较NSDates的方法：
#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
并执行：
#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
简单易用：
if([aDateYouWantToCompare isEarlierThanOrEqualTo:[NSDate date]]) // [NSDate date] is now { // do your thing ... }
通过这种方法也可以比较两个date
NSDate * dateOne = [NSDate date]; NSDate * dateTwo = [NSDate date]; if([dateOne compare:dateTwo] == NSOrderedAscending) { }
如果你使两个dateNSDate s你可以使用NSDate的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");
你可以看看这里的文档。
我发现的最好的方法是检查给定的date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];
根据苹果date和时间编程指南中的日历计算列表13 [NSCalendar ordinalityOfUnit：NSDayCalendarUnit inUnit：NSEraCalendarUnit forDate：myDate]给出了自时代开始以来的中午数量。 这样就很容易检查date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; } }
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……
在Cocoa中，为了比较date，在NSDate对象上使用isEqualToDate ， compare ， laterDate和earlierDate方法之一，用你需要的date实例化。
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/Classes/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/compare：;
你真正需要的是比较两个同类的对象。
-
从stringdate（@“2009-05-11”）中创build一个NSDate：
http://blog.evandavey.com/2008/12/how-to-convert-a-string-to-nsdate.html -
如果当前date也是一个string，使它成为一个NSDate。 如果它已经是一个NSDate，离开它。
这是帕斯卡答案中的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())
如果其他人正在寻找的话，那么将Naveed Rafi的答案转换成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) }
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date。
..
NSString *date = @"2009-05-11" NSString *nowDate = [[[NSDate date]description]substringToIndex: 10]; if([date isEqualToString: nowDate]) { // your code }
