确定NSPredicate中是否存在NSDate [英] Determining if an NSDate is today in NSPredicate

问题描述

我已经在该站点上尝试了多种方法并尝试了一些建议，但是如何确定CoreData属性 dueDate是否等于 Today，我也知道NSDate也是一个特定时间，但是我想要谓词如果是同一天/月/年，则返回该值，而不管一天中的时间。有任何建议吗？

I've tried multiple methods and tried some suggestions on this site, but how can I determine if a CoreData attribute "dueDate" is equal to "Today", I know NSDate is a specific time as well but I want the predicate to return if it is the same day/month/year regardless of what the time is in the day. Any suggestions?

推荐答案

这是我想出的：

- (NSPredicate *)matchAttribute:(NSString *)attributeName withDate:(NSDate *)date
{
    NSDateComponents *components = [[NSCalendar currentCalendar] components:NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit fromDate:date];
    NSDateComponents *oneDay = [[NSDateComponents alloc] init];
    oneDay.day = 1;

    NSDate *lastMidnight = [[NSCalendar currentCalendar] dateFromComponents:components];
    NSDate *nextMidnight = [[NSCalendar currentCalendar] dateByAddingComponents:oneDay toDate:lastMidnight options:NSWrapCalendarComponents];

    return [NSPredicate predicateWithFormat:@"(%K >= %@) AND (%K <= %@)", attributeName, lastMidnight, attributeName, nextMidnight];
}

灵感来自此处，此处和此处。

这篇关于确定NSPredicate中是否存在NSDate的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！