ios - NSPredicate 用于多天全天事件

Question

在我的数据库中，我有两列，即 startDate 和 endDate，如果用户在 UI 中按下任何日期(例如 2015 年 7 月 16 日)，那么它应该获取 startDate 和 endDate 之间的所有事件。

之前我写了一个用于获取凝视事件的谓词:

[NSPredicate predicateWithFormat:[NSString stringWithFormat:@"%@ >= %%@ AND %@ < %%@", @"startTime", @"endTime"], date, [date dateForNextDay]]

但是如果给定日期不是事件的开始日期，上述查询将不起作用。

例子: 如果我的 session 日期为 7/13 - 7/16 并且给定日期为 7/14，则 session 事件应该能够使用谓词获取。我的旧查询仅适用于 7 月 13 日。它应该在给定日期获取该事件 - 7/13、7/14、7/15、7/16

Answer 1

获取给定日期大于或等于给定日期且小于或等于给定日期的事件...

[NSPredicate predicateWithFormat:@"%@ >= startTime AND %@ <= endTime", date, date]

编辑...使用一个简单的对象进行测试，确认其工作正常...

- (NSArray *)filterArray:(NSArray *)array forDate:(NSDate *)date {
    NSPredicate *p = [NSPredicate predicateWithFormat:@"%@ >= startTime AND %@ <= endTime", date, date];
    return [array filteredArrayUsingPredicate:p];
}

- (void)testPredicate {

    NSDictionary *event0 = @{ @"startTime":[self dateFromString:@"07/01/2015"], @"endTime":[self dateFromString:@"07/04/2015"] };
    NSDictionary *event1 = @{ @"startTime":[self dateFromString:@"07/10/2015"], @"endTime":[self dateFromString:@"07/14/2015"] };
    NSDictionary *event2 = @{ @"startTime":[self dateFromString:@"08/02/2015"], @"endTime":[self dateFromString:@"08/09/2015"] };

    NSArray *events = @[event0, event1, event2];

    NSDate *july9 = [self dateFromString:@"07/09/2015"];
    NSDate *july10 = [self dateFromString:@"07/10/2015"];
    NSDate *july11 = [self dateFromString:@"07/11/2015"];
    NSDate *july13 = [self dateFromString:@"07/13/2015"];
    NSDate *july14 = [self dateFromString:@"07/14/2015"];
    NSDate *july15 = [self dateFromString:@"07/15/2015"];

    NSLog(@"filtered using 9 should be empty %@", [self filterArray:events forDate:july9]);
    NSLog(@"filtered using 10 should hit %@", [self filterArray:events forDate:july10]);
    NSLog(@"filtered using 11 should hit %@", [self filterArray:events forDate:july11]);
    NSLog(@"filtered using 13 should hit %@", [self filterArray:events forDate:july13]);
    NSLog(@"filtered using 14 should hit %@", [self filterArray:events forDate:july14]);
    NSLog(@"filtered using 15 should be empty %@", [self filterArray:events forDate:july15]);
}

- (NSDate *)dateFromString:(NSString *)string {
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"MM/dd/yyyy"];
    return [dateFormatter dateFromString:string];
}

前述内容不需要对午夜情况进行特殊处理即可按照问题建议执行(包括最后一个结束时间)。

这会生成以下日志输出，您可以自己确认...

filtered using 9 should be empty ()
filtered using 10 should hit (
        {
        endTime = "2015-07-14 07:00:00 +0000";
        startTime = "2015-07-10 07:00:00 +0000";
    }
)
filtered using 11 should hit (
        {
        endTime = "2015-07-14 07:00:00 +0000";
        startTime = "2015-07-10 07:00:00 +0000";
    }
)
filtered using 13 should hit (
        {
        endTime = "2015-07-14 07:00:00 +0000";
        startTime = "2015-07-10 07:00:00 +0000";
    }
)
filtered using 14 should hit (
        {
        endTime = "2015-07-14 07:00:00 +0000";
        startTime = "2015-07-10 07:00:00 +0000";
    }
)
filtered using 15 should be empty ()