NSDate,比较两个日期

Question

好的,我已经在这几天工作了,而且我被卡住了.我想要做的是将当前时间与预定时间进行比较.我想要发生的是,每天在某些时候我想要触发某些代码,但不是在我指定的时间之前.

因此,基本上如果"当前时间"与"预定时间"相同或相等,则触发此代码.或者解雇这行代码.

听起来很简单,但我在抓两次比较时遇到了麻烦.

我已经将字符串格式化为这样的日期

     NSString* dateString = @"11:05 PM";
        NSDateFormatter* firstDateFormatter = [[[NSDateFormatter alloc] init] autorelease];
        [firstDateFormatter setDateFormat:@"h:mm a"];
        [firstDateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
        NSDate* date = [firstDateFormatter dateFromString:dateString];
        NSLog(@"date %@",date);

然后我像这样抓住当前的时间

   NSDate *currentTime = [NSDate dateWithTimeIntervalSinceNow:[[NSTimeZone localTimeZone]     secondsFromGMT]];
NSDateComponents* comps = [[NSCalendar currentCalendar] 
                           components: NSHourCalendarUnit |NSMinuteCalendarUnit 
                                |NSSecondCalendarUnit fromDate:currentTime];
 [[NSCalendar currentCalendar] dateFromComponents:comps];

那我该怎么比较这两次呢？我已经尝试了我能想到的一切,请帮忙.

Answer 1

你可以尝试下面的代码行吗？

switch ([dateOne compare:dateTwo]){
     case NSOrderedAscending:
          NSLog(@"NSOrderedAscending");
    break;
    case NSOrderedSame:
          NSLog(@"NSOrderedSame");
    break;
    case NSOrderedDescending:
         NSLog(@"NSOrderedDescending");
    break;
}

但在你的情况下,我认为你需要保持两个日期相同的格式..或者像这样的事情

 NSDateComponents *components = [[NSCalendar currentCalendar] components:NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit fromDate:[NSDate date]];
    [components setHour:23];//change your time to 24hrs formate 
    [components setMinute:05];
    [components setSecond:00];


    NSDate *dateOne = [[NSCalendar currentCalendar] dateFromComponents:components];

    components = [[NSCalendar currentCalendar] components:NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit fromDate:[NSDate date]];

     NSDate *dateTwo = [[NSCalendar currentCalendar] dateFromComponents:components];

并在dateOne和dateTwo之间进行比较.