Swift 3 ObjectOriented Programming - Second Edition

Generating computed properties with setters and getters

As previously explained, we don't want a user of our superhero class to be able to change a superhero's birth year after an instance is initialized because the superhero won't be born again at a different date. In fact, we want to calculate the superhero's age and make it available to users. We use an approximated age in order to keep the focus on the properties and don't complicate our lives with the manipulation of complete dates and the Date class.

We can define a property called age with a getter method but without a setter method; that is, we will create a read-only computed property. This way, it is possible to retrieve the superhero's age, but we cannot change it because there isn't ...