Question

在我的应用中，我有UITableView with个部分。每个实体对象都基于名为“sectionIdentifier”的瞬态属性进行排序，该属性在名为ToDoItem.m的NSManagedObject子类中定义。启动应用程序后，所有对象都会正确排序并显示在预期的部分下。在表视图控制器上有添加按钮以添加新对象，在点击它之后，应用程序抛出以下警告：

2014-01-15 11:19:19.459 To-Do Pro Light[21914:a0b] date= (null)
2014-01-15 11:19:19.461 To-Do Pro Light[21914:a0b] todayDate = 2014-01-15 18:19:19 +0000
2014-01-15 11:19:19.473 To-Do Pro Light[21914:a0b] *** -[__NSCFCalendar components:fromDate:]: date cannot be nil

我的意思是，你觉得这个操作应该用零日期来表示什么？目前已经避免了例外。这个投诉会报告其中一些错误，然后进一步的违规行为只会默默地做任何随机的事情。这是此次发生的回溯（由于编译器优化，某些帧可能会丢失）：

(
    0   CoreFoundation                      0x01ab8475 -[__NSCFCalendar components:fromDate:] + 101
    1   CoreFoundation                      0x01b5496c -[_NSCopyOnWriteCalendarWrapper components:fromDate:] + 92
    2   To-Do Pro Light                     0x00008e95 -[ToDoItem sectionIdentifier] + 357
    3   Foundation                          0x0145b947 _NSGetUsingKeyValueGetter + 119
    4   CoreData                            0x0029d75a _PF_Handler_Public_GetProperty + 122
    5   CoreData                            0x0029d685 -[NSManagedObject valueForKey:] + 149
    6   Foundation                          0x0147aa5a -[NSObject(NSKeyValueCoding) valueForKeyPath:] + 409
    7   CoreData                            0x003696ed -[NSFetchedResultsController(PrivateMethods) _objectInResults:] + 77
    8   CoreData                            0x00369995 -[NSFetchedResultsController(PrivateMethods) _preprocessInsertedObjects:insertsInfo:newSectionNames:] + 389
    9   CoreData                            0x0036c1bd -[NSFetchedResultsController(PrivateMethods) _managedObjectContextDidChange:] + 1197
    10  Foundation                          0x01500bf9 __57-[NSNotificationCenter addObserver:selector:name:object:]_block_invoke + 40
    11  CoreFoundation                      0x01b06524 __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 20
    12  CoreFoundation                      0x01a5e00b _CFXNotificationPost + 2859
    13  Foundation                          0x0143a951 -[NSNotificationCenter postNotificationName:object:userInfo:] + 98
    14  CoreData                            0x00271173 -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:] + 83
    15  CoreData                            0x0031078f -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:withDeletions:withUpdates:withRefreshes:] + 367
    16  CoreData                            0x0026c608 -[NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:] + 2152
    17  CoreData                            0x0026bd99 -[NSManagedObjectContext processPendingChanges] + 41
    18  CoreData                            0x0023ffe1 _performRunLoopAction + 321
    19  CoreFoundation                      0x01a724ce __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 30
    20  CoreFoundation                      0x01a7241f __CFRunLoopDoObservers + 399
    21  CoreFoundation                      0x01a50344 __CFRunLoopRun + 1076
    22  CoreFoundation                      0x01a4fac3 CFRunLoopRunSpecific + 467
    23  CoreFoundation                      0x01a4f8db CFRunLoopRunInMode + 123
    24  GraphicsServices                    0x038bb9e2 GSEventRunModal + 192
    25  GraphicsServices                    0x038bb809 GSEventRun + 104
    26  UIKit                               0x0059bd3b UIApplicationMain + 1225
    27  To-Do Pro Light                     0x000078ad main + 141
    28  libdyld.dylib                       0x020e6725 start + 0
)
2014-01-15 11:19:19.478 To-Do Pro Light[21914:a0b] Tmp= 0
2014-01-15 11:19:19.524 To-Do Pro Light[21914:a0b] Fecha del todo = 2014-01-15 18:19:19 +0000

我无法理解，但在唯一的文件中，日历组件位于ToDoItem.m NSManagedObject类中，我向您展示：

#import "ToDoItem.h"
#import "ToDoGroup.h"
#import "ToDoSubItem.h"


@implementation ToDoItem

@dynamic todoDescription;
@dynamic todoName;
@dynamic todoDueDate;
@dynamic sectionIdentifier;
@dynamic todogroup;
@dynamic todosubitems;



-(NSString *)sectionIdentifier{

    [self willAccessValueForKey:@"sectionIdentifier"];
    NSString *tmp = [self primitiveValueForKey:@"sectionIdentifier"];
    [self didAccessValueForKey:@"sectionIdentifier"];

    if (!tmp){

        NSDate *date = self.todoDueDate;
        NSDate *todayDate = [NSDate date];

        NSLog(@"date= %@",date);
        NSLog(@"todayDate = %@",todayDate);


        NSCalendar *calendar = [NSCalendar currentCalendar];
        NSInteger comps = (NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit);
        NSDateComponents *date1Components = [calendar components:comps fromDate:date];
        NSDateComponents *date2Components = [calendar components:comps fromDate:todayDate];
        date = [calendar dateFromComponents:date1Components];
        todayDate = [calendar dateFromComponents:date2Components];




        if([date
            compare:todayDate] == NSOrderedSame) {
            tmp = @"1";//TODAY
        }
        else if([date
                 compare:todayDate] == NSOrderedDescending){
            tmp = @"2";//OVERDUE
        }
        else if ([date
                  compare:todayDate] == NSOrderedAscending){
            tmp =@"0";//UPCOMING
        }
        NSLog(@"Tmp= %@",tmp);

        [self setPrimitiveValue:tmp forKey:@"sectionIdentifier"];

    }
    return tmp;

}

@end

欢迎任何帮助，如果你想让我向你展示我的tableView控制器，没问题..... 提前谢谢。

Answer 1

这意味着

 NSDate *date = self.todoDueDate;

返回nil，即您没有为新创建的对象设置todoDueDate。

您无法从nil日期计算日期组件。

核心数据对象未正确更新或发出定义日期组件

1 个答案: