NSPredicate两个日期之间的范围没有按预期工作 [英] NSPredicate for range between two dates is not working as expected

问题描述

我有两个 NSDate s：

NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:@"MM/dd/yyyy"];
NSDate *rangeStart = [df dateFromString: @"03/03/2013"];
NSDate *rangeEnd = [df dateFromString: @"10/04/2013"];

这个谓词：

request.predicate = [NSPredicate predicateWithFormat:@"createdDate >= %@ AND createdDate <= %@", rangeStart, rangeEnd];

但即使谓词的第二部分专门使用< = 它返回对象直到前一天（即 10/03/2013 ）。

But even though the second part of the predicate specifically uses a <= it is returning objects up until the day before (that is 10/03/2013).

我也尝试构造这样的谓词：

I also tried constructing the predicate like this:

NSPredicate *dateStartPredicate = [NSPredicate predicateWithFormat:@"createdDate >= %@", rangeStart];
NSPredicate *dateEndPredicate = [NSPredicate predicateWithFormat:@"createdDate <= %@", rangeEnd];
NSPredicate *finalPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObjects:dateStartPredicate, dateEndPredicate, nil]]; 

但我得到了相同的结果。难道我做错了什么？这实际上是预期的行为吗？如果是，如何将 rangeEnd 设置为第二天？

But I'm getting the same results. Am I doing something wrong? Is this actually the expected behavior? If it is, how can set the rangeEnd to the next day?

谢谢

推荐答案

NSDate 对象也包括时间。当您将没有时间的日期传递给 dateFromString：方法时，假定相应日期的午夜，即只有午夜时发生的项目将返回 true 小于或等于表达式。

NSDate objects include the time as well. When you pass a date with no time to the dateFromString: method, the midnight of the corresponding day is assumed, i.e. only the items that happen on midnight would return true in the less than or equal expression.

有两种常用方法可以解决它：

There are two common ways of solving it:

• 将一天添加到 rangeEnd ，并使用小于而不是小于或等于，或


• 将时间添加到 rangeEnd 日期（这不太理想，因为您需要在长字符串中指定时间，或错过当天最后一秒发生的事情。）

• Add one day to rangeEnd, and use "less than" instead of "less than or equal", or
• Add the time to the rangeEnd date (this is not ideal, because you would either need to specify the time in a long string, or miss the items that happened on the last second of the day).

以下是使用第一种方法的方法：

Here is how to use the first approach:

request.predicate = [NSPredicate
    predicateWithFormat:@"createdDate >= %@ AND createdDate < %@"
    , rangeStart
    , [rangeEnd dateByAddingTimeInterval:60*60*24]
];

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