Missing code on page 72


#1

It seems that in the program on page 72, there should be a line:

calculator.container = backpack;

Otherwise with the current program, the destroy still happens.


#2

You may have missed the code on page 71. In this chapter, when you override the setter for containedItem, the reciprocal relationship is also set up:

- (void)setContainedItem:(BNRItem *)item
{
    _containedItem = item;

    // When given an item to contain, the contained
    // item will be given a pointer to its container
    item.container = self;
}