小编use*_*951的帖子

我是初学者,正在使用Core Data for iOS.我正在尝试在这里创建一个库函数,但是我收到了这条消息:

'NSInvalidArgumentException', reason: 
    'Unacceptable type of value for ordered to-many relationship: property 
    = "studenthistory"; desired type = NSOrderedSet; given type = __NSSetI; 
    value = {(
      <NSManagedObject: 0x8cacd20> (entity: StudentHistory; id: 0x8cacd80 
      <x-coredata:///StudentHistory/tE710FEAD-C78E-4C91-8F38-23BDC5AA2C943> ; 
      data: {
        bookid = 5;
        checkin = 6;
        checkout = 7;
        open = TBA;
        student = nil;

关系是学生 - >(对许多人) - > StudentHistory.

我只能猜测,但我怀疑问题正在发生,试图设置一个对象,而期待更多,因为它是一个NSSet？

这是代码:

...
StudentHistory *stuhist = [NSEntityDescription insertNewObjectForEntityForName:@"StudentHistory" inManagedObjectContext:self.managedObjectContext];

stuhist.bookid = _bookidTextField.text;
stuhist.checkout = _checkoutTextField.text;
stuhist.checkin = _checkinTextField.text;
stuhist.open …