Overriding properties

First, we will try to override the numberOfLegs type property that the Dog class will inherit from the Animal base class. We will face an issue and solve it. The following lines show the code for a simplified version of the Dog class that inherits from DomesticMammal and just tries to override the numberOfLegs type property:

public class Dog: DomesticMammal {
    public static override var numberOfLegs: Int {
        get {
            return 4;
        }
    }
}

After we enter the previous lines in the Playground, we will see the following error message in the line that tries to override the numberOfLegs type property: error: class var overrides a 'final' class var. The following screenshot shows the error in the Playground:

Tip

When we declare either a type property or method with the static keyword in a base class, it isn't possible to override it in a subclass. Thus, if we want to enable either a type property or method to be overridden in the subclasses, it is necessary...