如何在NSTimeInterval上使用谓词？

Question

我想获得当月的所有记录,因此我将该月的第一个日期和该月的最后一天的两个谓词堆叠起来.由于我使用CoreData,因此日期实际存储为NSTimeInterval.

NSCalendar *calendar = [NSCalendar currentCalendar];

//Get beginning of current month
NSDateComponents *beginningOfCurrentMonthComponents = [calendar components:(NSEraCalendarUnit | NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit) fromDate:date];
[beginningOfCurrentMonthComponents setDay:1];
NSDate *beginningOfCurrentMonthDate = [calendar dateFromComponents:beginningOfCurrentMonthComponents];

//Set a single month to be added to the current month
NSDateComponents *oneMonth = [[NSDateComponents alloc] init];
[oneMonth setMonth:1];

//determine the last day of this month
NSDate *beginningOfNextMonthDate = [calendar dateByAddingComponents:oneMonth toDate:beginningOfCurrentMonthDate options:0];

NSMutableArray *parr = [NSMutableArray array];
[parr addObject:[NSPredicate predicateWithFormat:@"recordDate >= %d", [beginningOfCurrentMonthDate timeIntervalSince1970]]];
[parr addObject:[NSPredicate predicateWithFormat:@"recordDate < %d", [beginningOfNextMonthDate timeIntervalSince1970]]];

//Give me everything from beginning of this month until end of this month
NSPredicate *predicate = [NSCompoundPredicate andPredicateWithSubpredicates:parr];

return [allRecords filteredArrayUsingPredicate:predicate];

返回已过滤的数组后,它会崩溃并显示以下错误消息:

2013-10-25 19:09:39.702 [3556:a0b] -[__NSCFNumber timeIntervalSinceReferenceDate]: unrecognized selector sent to instance 0x8911440
2013-10-25 19:09:39.704 [3556:a0b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFNumber timeIntervalSinceReferenceDate]: unrecognized selector sent to instance 0x8911440'
*** First throw call stack:
(
    0   CoreFoundation                      0x01aa85e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x0182b8b6 objc_exception_throw + 44
    2   CoreFoundation                      0x01b45903 -[NSObject(NSObject) doesNotRecognizeSelector:] + 275
    3   CoreFoundation                      0x01a9890b ___forwarding___ + 1019
    4   CoreFoundation                      0x01a984ee _CF_forwarding_prep_0 + 14
    5   CoreFoundation                      0x01a7e3e3 -[NSDate compare:] + 67
    6   Foundation                          0x014194fe -[NSComparisonPredicateOperator performPrimitiveOperationUsingObject:andObject:] + 408
    7   Foundation                          0x014b03de -[NSPredicateOperator performOperationUsingObject:andObject:] + 306
    8   Foundation                          0x014b016c -[NSComparisonPredicate evaluateWithObject:substitutionVariables:] + 347
    9   Foundation                          0x014299b6 -[NSCompoundPredicateOperator evaluatePredicates:withObject:substitutionVariables:] + 240
    10  Foundation                          0x01429845 -[NSCompoundPredicate evaluateWithObject:substitutionVariables:] + 294
    11  Foundation                          0x014b0009 -[NSPredicate evaluateWithObject:] + 48
    12  Foundation                          0x014aff89 _filterObjectsUsingPredicate + 418
    13  Foundation                          0x014afd42 -[NSArray(NSPredicateSupport) filteredArrayUsingPredicate:] + 328

我也用这个循环表示recordDate确实存在于数组中:

for (FTRecord *r in allRecords) {
    NSLog(@"%f", [r recordDate]);
}

2013-10-25 19:09:35.860 [3556:a0b] 1380582000.000000
2013-10-25 19:09:36.556 [3556:a0b] 1380754800.000000

Answer 1

创建管理对象子类时,使recordDate表示为您选择了"使用标属性基本数据类型"选项 NSTimeInterval中的FTRecord类.

但是在谓词中"recordDate >= 123.45",左侧存储为a NSKeyPathExpression,valueForKeyPath:@"recordDate"用于访问返回NSDate对象的属性.该谓词的右侧存储为对象NSConstantValueExpression 的引用NSNumber.因此将a NSDate与a进行比较NSNumber,这恰好导致您获得的异常.

要解决这个问题,你必须将属性与NSDate (比较@rmaddy最初建议的)进行比较:

[parr addObject:[NSPredicate predicateWithFormat:@"recordDate >= %@", beginningOfCurrentMonthDate]];
[parr addObject:[NSPredicate predicateWithFormat:@"recordDate < %@", beginningOfNextMonthDate]];
NSPredicate *predicate = [NSCompoundPredicate andPredicateWithSubpredicates:parr];

我对此进行了测试,似乎产生了预期的结果.

但请注意,Core Data使用timeIntervalSinceReferenceDate和 dateWithTimeIntervalSinceReferenceDate转换标量值NSDate,而不是timeIntervalSince1970.