ios - 日期未保存到核心数据对象

Question

我正在从 NSSting 转换 NSDate，然后以这种方式将这个日期添加到 Core Data 对象

- (IBAction)save:(id)sender
{

    managedObjectContext = [AppDelegate sharedDelegate].managedObjectContext;

    NSUInteger selectedString = [subjectPicker selectedRowInComponent:0];

    Subjects *selectedSubject = [subjectForEventArray objectAtIndex:selectedString];

    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc]init];
    dateFormatter.timeZone = [NSTimeZone timeZoneWithName:@"Europe/Kyiv"];
    [dateFormatter setDateFormat:@"hh:mm"];

    NSLog(@" %@ %@ ", self.startDateForSubject, self.endDateForSubject);
    NSDate *sDate = [dateFormatter dateFromString:self.startDateForSubject];
    NSDate *eDate = [dateFormatter dateFromString:self.endDateForSubject];


    NSLog(@"%@ %@", eDate, sDate);


    selectedSubject.timeOfSubject.startDate = sDate;
    selectedSubject.timeOfSubject.endDate = eDate;
    selectedSubject.weekDay.dayOfWeek = _dayString;





    NSError *error;

    if ([managedObjectContext save:&error])
    {
        if (self.delegate) {
            [self.delegate selectedTeacherToControllerForIndexPath:self.scheduleCellIndexPath];
        } else {
            NSLog(@"delegate is not set and can not execute code");
        }
          NSLog(@"=== %@ === %@ === %@ ===",selectedSubject.timeOfSubject.startDate, selectedSubject.timeOfSubject.endDate, selectedSubject.weekDay.dayOfWeek);
        [self.navigationController popViewControllerAnimated:YES];
    }


}

这是日志窗口

2014-12-02 18:35:00.115 StudentSchedule[1003:38141]  04:50 06:45 
2014-12-02 18:35:00.117 StudentSchedule[1003:38141] 2000-01-01 04:45:00 +0000 2000-01-01 02:50:00 +0000
2014-12-02 18:35:00.118 StudentSchedule[1003:38141] === (null) === (null) === Monday, 11.12 ===

NSManagedObject 子类 Subjects 与另一个表“TimeOfSchedule”有关系 timeOfSubject，并且我有属性 NSDate。

@class ReadySubject, Teacher, TimeOfSchedule;

@interface Subjects : NSManagedObject

@property (nonatomic, retain) NSString * article;
@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) NSString * type;
@property (nonatomic, retain) Teacher *teacherOfSubject;
@property (nonatomic, retain) TimeOfSchedule *timeOfSubject;

和

@class Subjects;

@interface TimeOfSchedule : NSManagedObject

@property (nonatomic, retain) NSDate * endDate;
@property (nonatomic, retain) NSDate * startDate;

问题是，这个日期没有保存在我的核心数据中，有空值，我不明白为什么？

Answer 1

看起来 timeOfSubject 为零。确保您的托管对象已正确设置和填充。

如果您设置了 timeOfSubject 的属性，它不会自动插入一个新的 TimeOfSchedule 对象作为关系。您必须使用 insertNewObject... 创建它。并将其附加到 Subjects 实体。

顺便说一句:您不应该将您的实体名称复数化，因为这不合逻辑且相当困惑。
请改用 Subject。

至于“正确设置”，您是否创建了从TimeOfSchedule 回到Subject 的反向关系？至少您在代码中将其遗漏了。