Declaring protocols

Now, it is time to code the protocols in Swift. We will code the following five protocols:

• ComicCharacter

• GameCharacter

• Alien

• Wizard

• Knight

The following UML diagram shows the five protocols that we will code in Swift with their required properties and methods included in the diagram:

The following lines show the code for the ComicCharacter protocol. The public modifier followed by the protocol keyword and the protocol name, ComicCharacter, composes the protocol declaration. As it happens with class declarations, the protocol body is enclosed in curly brackets ({}):

public protocol ComicCharacter {
    var nickName: String { get set }

    func drawSpeechBalloon(message: String)
    func drawSpeechBalloon(destination: ComicCharacter, message: String)
    func drawThoughtBalloon(message: String)
}

The protocols declare a nickName read/write String stored property requirement, a drawSpeechBaloon method requirement overloaded twice, and a drawThoughtBalloon method requirement...