Question

我使用以下代码来比较两个NSDates。结果稍后在transient属性中用于组织表视图部分中的对象。我可以确保核心数据存储中有足够的对象，以便存在三个可能的结果，但NSLog显示选项tmp = @“1”，从不抛出。

-(NSString *)sectionIdentifier{

    [self willAccessValueForKey:@"sectionIdentifier"];
    NSString *tmp = [self primitiveValueForKey:@"sectionIdentifier"];
    [self didAccessValueForKey:@"sectionIdentifier"];

    if (!tmp){

        NSDate *date = self.todoDueDate;
        NSDate *todayDate = [NSDate date];

        NSLog(@"date= %@",date);
        NSLog(@"todayDate = %@",todayDate);



        if([date
            compare:todayDate] == NSOrderedSame) {
            tmp = @"1";//TODAY
        }
        else if([date
                 compare:todayDate] == NSOrderedDescending){
            tmp = @"2";//OVERDUE
        }
        else if ([date
                  compare:todayDate] == NSOrderedAscending){
            tmp =@"0";//UPCOMING
        }
        NSLog(@"Tmp= %@",tmp);

        [self setPrimitiveValue:tmp forKey:@"sectionIdentifier"];

    }

这里是日志：

2014-01-15 10:10:52.732 To-Do Pro Light[21458:a0b] date      = 2014-01-10 19:53:19 +0000
2014-01-15 10:10:52.735 To-Do Pro Light[21458:a0b] todayDate = 2014-01-15 17:10:52 +0000
2014-01-15 10:10:52.742 To-Do Pro Light[21458:a0b] Tmp= 0
2014-01-15 10:10:52.743 To-Do Pro Light[21458:a0b] date      = 2014-01-14 17:45:45 +0000
2014-01-15 10:10:52.746 To-Do Pro Light[21458:a0b] todayDate = 2014-01-15 17:10:52 +0000
2014-01-15 10:10:52.747 To-Do Pro Light[21458:a0b] Tmp= 0
2014-01-15 10:10:52.748 To-Do Pro Light[21458:a0b] date      = 2014-01-14 17:57:44 +0000
2014-01-15 10:10:52.749 To-Do Pro Light[21458:a0b] todayDate = 2014-01-15 17:10:52 +0000
2014-01-15 10:10:52.751 To-Do Pro Light[21458:a0b] Tmp= 0
2014-01-15 10:10:52.753 To-Do Pro Light[21458:a0b] date      = 2014-01-15 16:31:48 +0000
2014-01-15 10:10:52.755 To-Do Pro Light[21458:a0b] todayDate = 2014-01-15 17:10:52 +0000
2014-01-15 10:10:52.756 To-Do Pro Light[21458:a0b] Tmp= 0
2014-01-15 10:10:52.758 To-Do Pro Light[21458:a0b] date      = 2014-01-15 16:32:06 +0000
2014-01-15 10:10:52.759 To-Do Pro Light[21458:a0b] todayDate = 2014-01-15 17:10:52 +0000
2014-01-15 10:10:52.761 To-Do Pro Light[21458:a0b] Tmp= 0
2014-01-15 10:10:52.762 To-Do Pro Light[21458:a0b] date      = 2014-01-15 17:03:40 +0000
2014-01-15 10:10:52.763 To-Do Pro Light[21458:a0b] todayDate = 2014-01-15 17:10:52 +0000
2014-01-15 10:10:52.764 To-Do Pro Light[21458:a0b] Tmp= 0
2014-01-15 10:10:52.766 To-Do Pro Light[21458:a0b] date      = 2014-01-15 18:33:48 +0000
2014-01-15 10:10:52.767 To-Do Pro Light[21458:a0b] todayDate = 2014-01-15 17:10:52 +0000
2014-01-15 10:10:52.768 To-Do Pro Light[21458:a0b] Tmp= 2

我做错了什么？

Answer 1

你永远不会得到完全匹配，因为两个NSDate对象必须在当天引用相同的MILLISECOND才能发生。最简单的方法是使用NSDateFormatter将日期格式化为yyyy / MM / dd，然后比较生成的字符串。

（不要忘记根据您的要求适当设置时区。）

Answer 2

NSDate *startDate = ...;
NSDate *endDate = ...;

NSCalendar *gregorian = [[NSCalendar alloc]
                 initWithCalendarIdentifier:NSGregorianCalendar];

NSUInteger unitFlags = NSMonthCalendarUnit | NSDayCalendarUnit | NSYearCalendarUnit;

NSDateComponents *components = [gregorian components:unitFlags
                                          fromDate:startDate
                                          toDate:endDate options:0];
NSInteger months = [components month];
NSInteger days = [components day];
NSInteger years = [components year];

如果所有三个都是0 - 日期是相等的。

更多信息 - https://developer.apple.com/library/ios/documentation/cocoa/Conceptual/DatesAndTimes/Articles/dtCalendricalCalculations.html#//apple_ref/doc/uid/TP40007836-SW1

比较iOS中的日期问题

2 个答案: