Question

我使用transient attribute在core data objects中分发table view sections。 transient attribute称为 sectionIdentifier ，它的定义取决于名为 todoDueDate 的属性。我需要以下列组中的所有必须包含的方式过滤对象并且仅在一个中

1. sectionIdentier = 0, **OVERDUE** , todoDueDate < today
2. sectionIdentier = 1, **TODAY** , todoDueDate = today
3. sectionIdentier = 2, **TOMORROW** , todoDueDate >today AND todoDueDate= = tomorrow
4. sectionIdentier = 3, **UPCOMING** , todoDueDate > today AND todoDueDate!=tomorrow

使用我当前的代码，我能够过滤案例1,2和4的对象（我必须在这里丢弃明天的对象）。我已经尝试了几种方法来过滤案例3的对象，但没有成功。我恳请你帮我过滤案例3。这是我目前的代码：

-(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);


        NSCalendar *calendar = [NSCalendar currentCalendar];
        NSInteger comps = (NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit);
        NSDateComponents *date1Components = [calendar components:comps fromDate:date];
        NSDateComponents *date2Components = [calendar components:comps fromDate:todayDate];

        date = [calendar dateFromComponents:date1Components];
        todayDate = [calendar dateFromComponents:date2Components];


        if([date
            compare:todayDate] == NSOrderedAscending) {
            tmp = @"0";//OVERDUE
        }
        if([date
          compare:todayDate] == NSOrderedDescending)  {
          tmp = @"3";//UPCOMING BUT NOT TOMORROW(PENDING THIS PART)
        }
        if ([date
             compare:todayDate] == NSOrderedSame) {
            tmp = @"1";//TODAY
        }


   //TOMORROW COMES HERE



        NSLog(@"Tmp= %@",tmp);

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

    }
    return tmp;

}

这是我更新的代码：

-(NSString *)sectionIdentifier{

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

    if (!tmp){
        NSDate *today = [NSDate date];
        NSDate *date = self.todoDueDate;
        NSCalendar *calendar;
        NSInteger daysAfterToday = [calendar components:NSDayCalendarUnit
                                               fromDate:today toDate:date options:0].day;
       // NSString *section;
        if (daysAfterToday < 0) {
            tmp  = @"0";
        } else if (daysAfterToday == 0) {
            tmp = @"1";
        } else if (daysAfterToday == 1) {
            tmp = @"2";
        } else {
            tmp = @"3";
        }


        NSLog(@"TODAY = %@", today);
        NSLog(@"DATE = %@", date);
        NSLog(@"DAYS AFTER TODAY = %ld",(long)daysAfterToday);

        NSLog(@"Tmp= %@",tmp);

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

    }
    return tmp;

}

这里记录结果：

2014-01-17 22:35:53.576 To-Do Pro Light[4124:a0b] TODAY = 2014-01-18 05:35:53 +0000
2014-01-17 22:35:53.619 To-Do Pro Light[4124:a0b] DATE = 2014-01-13 04:08:32 +0000
2014-01-17 22:35:53.656 To-Do Pro Light[4124:a0b] DAYS AFTER TODAY = 0
2014-01-17 22:35:53.664 To-Do Pro Light[4124:a0b] Tmp= 1
2014-01-17 22:35:53.739 To-Do Pro Light[4124:a0b] TODAY = 2014-01-18 05:35:53 +0000
2014-01-17 22:35:53.743 To-Do Pro Light[4124:a0b] DATE = 2014-01-18 04:13:39 +0000
2014-01-17 22:35:53.748 To-Do Pro Light[4124:a0b] DAYS AFTER TODAY = 0
2014-01-17 22:35:53.752 To-Do Pro Light[4124:a0b] Tmp= 1
2014-01-17 22:35:53.757 To-Do Pro Light[4124:a0b] TODAY = 2014-01-18 05:35:53 +0000
2014-01-17 22:35:53.762 To-Do Pro Light[4124:a0b] DATE = 2014-01-19 04:16:14 +0000
2014-01-17 22:35:53.766 To-Do Pro Light[4124:a0b] DAYS AFTER TODAY = 0
2014-01-17 22:35:53.770 To-Do Pro Light[4124:a0b] Tmp= 1
2014-01-17 22:35:53.776 To-Do Pro Light[4124:a0b] TODAY = 2014-01-18 05:35:53 +0000
2014-01-17 22:35:53.779 To-Do Pro Light[4124:a0b] DATE = 2014-01-25 04:11:34 +0000
2014-01-17 22:35:53.825 To-Do Pro Light[4124:a0b] DAYS AFTER TODAY = 0
2014-01-17 22:35:53.831 To-Do Pro Light[4124:a0b] Tmp= 1

Answer 1

稍微改进一下代码，你可以使用消息dateOnly只返回一个日期，没有时间组件（将所有这些代码放在NSDate类别中）：

-(NSDate *)dateOnly {
  unsigned int flags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit;
  NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
  NSDateComponents *components = [calendar components:flags fromDate:self];
  return [calendar dateFromComponents:components];
}

今天会回复你：

+(NSDate *)today {
  return [[NSDate now] dateOnly];
}

然后，鉴于此：

-(NSDate *)addDays:(NSInteger)days {
  NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
  [offsetComponents setDay:days];
  return [[NSDate calendar] dateByAddingComponents:offsetComponents toDate:self options:0];
}

明天你可以：

+(NSDate *)tomorrow {
  return [[NSDate today] addDays:1];
}

通过此，您可以使用[NSDate today]和[NSDate tomorrow]来简化代码。

另外，请记住从todoDueDate：

中删除时间组件

NSDate *date = [self.todoDueDate dateOnly];
NSDate *todayDate = [NSDate today];
NSDate *tomorrowDate = [NSDate tomorrow];

您的逻辑可以简化：

sectionIdentier = 0， OVERDUE ，todoDueDate＆lt;今天
sectionIdentier = 1， TODAY ，todoDueDate = today
sectionIdentier = 2， TOMORROW ，todoDueDate =明天
sectionIdentier = 3， UPCOMING ，todoDueDate＆gt;明天

在代码中：

if ([date compare:todayDate] == NSOrderedAscending) {
  tmp = @"0";//OVERDUE
}
else if ([date isEqualToDate:todayDate])  {
  tmp = @"1";//TODAY
}
else if ([date isEqualToDate:tomorrowDate])  {
  tmp = @"2";//TOMORROW
}
else if ([date compare:tomorrowDate] == NSOrderedDescending)  {
  tmp = @"3";//UPCOMING
}

Answer 2

只需要求日历计算从今天到截止日期的天数，然后检查该号码：

        NSInteger daysAfterToday = [calendar components:NSDayCalendarUnit
            fromDate:today toDate:date options:0].day;
        NSString *section;
        if (daysAfterToday < 0) {
            section = @"0";
        } else if (daysAfterToday == 0) {
            section = @"1";
        } else if (daysAfterToday == 1) {
            section = @"2";
        } else {
            section = @"3";
        }

NSDate过滤案例

2 个答案: