Now that we understand the different ways in which data is represented in Swift, we can look into how we can manage the memory better. Every instance that we create takes up memory. Naturally, it wouldn't make sense to keep all data around forever. Swift needs to be able to free up memory so that it can be used for other purposes, once our program doesn't need it anymore. This is the key to managing memory in our apps. We need to make sure that Swift can free up all the memory that we no longer need, as soon as possible.
The way that Swift knows it can free up memory is when the code can no longer access an instance. If there is no longer any variable or constant referencing an instance, it can be repurposed for another instance. This is called "freeing the memory" or "deleting the object".
In Chapter 3, One Piece at a Time – Types, Scopes, and Projects we already discussed when a variable is accessible or not in the section about scopes. This makes memory management...