Understanding automatic reference counting

Automatic reference counting is very easy to understand. Imagine that we have to distribute the items that we store in a box. After we distribute all the items, we must throw the box in a recycle bin. We cannot throw the box in the recycle bin when we still have one or more items in it. Seriously, we don't want to lose the items we have to distribute because they are very expensive.

The problem has a very easy solution; we just need to count the number of items that remain in the box. When the number of items in the box reaches zero, we can get rid of the box.

Note

One or more variables can hold a reference to a single instance of a class. Thus, it is necessary to count the number of references to an instance before Swift can get rid of an instance. When the number of references to a specific instance reaches zero, Swift can automatically and safely remove the instance from memory because nobody needs this specific instance anymore.

For example, you...