This isn t an error - it is a feature of Core Data called faulting . Here is Apple s description:

Faulting reduces the amount of memory your application consumes. A fault is a placeholder object that represents a managed object that has not yet been fully realized, or a collection object that represents a relationship:

A managed object fault is an instance of the appropriate class, but its persistent variables are not yet initialized. A relationship fault is a subclass of the collection class that represents the relationship. Faulting allows Core Data to put boundaries on the object graph. Because a fault is not realized, a managed object fault consumes less memory, and managed objects related to a fault are not required to be represented in memory at all.

如果你想要看到每个单位的反对,那么你将不得不具体接触它们。 如下:

for (Order *order in fetchedObjects) {
    for (Unit *unit in [order units]) {
       NSLog(@"%@", unit);
       //I am not at a computer, so I cannot test, but this should work. You might have to access each property of the unit object to fire the fault, but I don t believe that is necessary.
    }
}     

为了,见to-many> relationship的所有物体,您可将其与>> 之间关系方法NSSet。

在您的具体情况下,在<条码>上打印第一期Units。 希望:

for (Order *order in fetchedObjects) {
    NSLog(@"%@", [order.units allObjects]);
    break;
}

尽快这样做:

for order in fetchedObjects {
    for unit in order.units.allObjects as [Unit] {
        println(unit)
    }
}

Yep, I had also the same problem. Try just print some field of this table, in example:

    for(Category *category in fetchedObjects) 
    {
        for(Cards *card in category.cards) 
        {
            NSLog(@"Question %@", card.question);
            NSLog(@"Card %@", card);
        }
    }

这非常反省。 我将我的头盔整整整天,直到我认识到,我无法勾画整个NSSet物体或每个NSManaged。 宗旨:

for (Order *order in fetchedObjects) {
   for (Unit *unit in [order units]) {
      NSLog(@"%@", unit);
   }
}

This will generate fault in xcode .. But If I print out each attribute in each NSMangedObject, it is fine. I guess Apple has memory concern over Auto-loading to-many objects. In a scenario where there is a chain of to-many relationships, it will consume a lot of memory. So need to lazy-load each attribute.

for (Order *order in fetchedObjects) {
   for (Unit *unit in [order units]) {
      NSLog(@"Unit Name : %@", unit.name);
   }
}

这将印刷单位名称。