Swift 4 Protocol-Oriented Programming - Third Edition

Using value and reference types

In this chapter, we implemented the vehicle types as structures, which are value types. We also mentioned that it may be preferable to implement these types as reference types. The reason we say this is instances of the vehicle types represent a single vehicle in our game and anytime something happens to that instance, such as taking damage from another vehicle, we would like that change to be persisted.

When we pass an instance of a value type to another part of our code, we are passing a copy of that instances and not the instance itself. This can cause problems when we want to persist changes that are applied to our types. Let's look at this problem with some code. We will start off by creating a function ...