Question

我想检查2 NSDate他们是否在同一天（时间可能不同）。我现在的目的是：

- (NSPredicate*) predicateWithDate:(NSDate *)date {
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit ) fromDate:date];
    //create a date with these components
    NSDate *startDate = [calendar dateFromComponents:components];
    [components setMonth:0];
    [components setDay:1];
    [components setYear:0];
    NSDate *endDate = [calendar dateByAddingComponents:components toDate:startDate options:0];
    return [NSPredicate predicateWithFormat:@"((ANY notes.date >= %@) AND (ANY notes.date < %@))",startDate,endDate];
}

Answer 1

你的startDate，endDate计算看起来几乎正确，你只忘了NSDayCalendarUnit：

NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:date];

有多种方法可以计算当天的开始和结束日期，我更喜欢以下略短的代码：

NSCalendar *calendar = [NSCalendar currentCalendar];
NSDate *startDate;
NSTimeInterval interval;
[calendar rangeOfUnit:NSDayCalendarUnit startDate:&startDate interval:&interval forDate:date];
NSDate *endDate = [startDate dateByAddingTimeInterval:interval];

您的谓词会找到所有带有date >= startDate注释的对象，以及date < endDate的任何（可能是不同的）音符。

如果要查找在给定日期至少有一个音符的对象，则需要提示：

[NSPredicate predicateWithFormat:@"SUBQUERY(notes, $n, $n.date >= %@ AND $n.date < %@).@count > 0",
           startDate,endDate];

NSPredicate用于检查同一日期

1 个答案: