Combining inheritance and protocols

We can combine class inheritance with protocol conformance. The following lines show the code for a new AngryCatAlien class that inherits from the AngryCat class and conforms to the Alien protocol. Note that the class declaration includes the superclass (AngryCat) and the implemented protocol (Alien) separated by a comma after the colon (:):

public class AngryCatAlien : AngryCat, Alien {
    public var numberOfEyes: Int = 0
    
    init (nickName: String, age: UInt, fullName: String, initialScore: UInt, x: UInt, y: UInt, numberOfEyes: Int) {
        super.init(nickName: nickName, age: age, fullName: fullName, initialScore: initialScore, x: x, y: y)
        self.numberOfEyes = numberOfEyes
    }
    
    public func appear() {
        print("I'm \(fullName) and you can see my \(numberOfEyes) eyes.")
    }
    
    public func disappear() {
        print("\(fullName) disappears.")
    }
}

As a result of the previous code, we have a new class named AngryCatAlien...