Command-Line Version of Magic 8 Ball written in Swift

Magic8BallCommandLine.swift

import Foundation

print("Welcome to Magic 8 Ball!")

var keepPlaying = true
while keepPlaying == true {

    // Prompt user to ask Magic 8 Ball a question
    print("What is your question? ")
    // We use the variable name '_' underbar below instead of something more
    // appropriate like 'question' in order to suppress Swift warnings
    // regarding the use of unused variables. Obviously, Magic 8 Ball
    // doesn't determine it's responses based on users questions, rather
    // answers are picked at random. However, we still need to prompt
    // the user to ask his or her question in order for the game to be fun.
    _ = readLine()!

    // Generate random integer to help us pick a random response
    let randomNumber:UInt32 = arc4random_uniform(20)

    // Initialize answer variable, then assign a value based on our random number
    var answer: String
    switch (randomNumber) {
        case 0:
            answer = "It is certain."
        case 1:
            answer = "It is decidedly so."
        case 2:
            answer = "Without a doubt."
        case 3:
            answer = "Yes, definitely."
        case 4:
            answer = "You may rely on it."
        case 5:
            answer = "As I see it, yes."
        case 6:
            answer = "Most Likely."
        case 7:
            answer = "Outlook good."
        case 8:
            answer = "Yes."
        case 9:
            answer = "Signs point to yes."
        case 10:
            answer = "Reply hazy try again."
        case 11:
            answer = "Ask again later."
        case 12:
            answer = "Better not tell you now."
        case 13:
            answer = "Cannot predict now."
        case 14:
            answer = "Concentrate and ask again."
        case 15:
            answer = "Don't count on it."
        case 16:
            answer = "My reply is no."
        case 17:
            answer = "My sources say no."
        case 18:
            answer = "Outlook not so good."
        case 19:
            answer = "Very doubtful."
        default:
            answer = "ERROR: PC LOAD LETTER"
    }

    // Display random response
    print(answer)

    // Ask user if he or she would like to play again
    // Prompt user to ask Magic 8 Ball a question
    print("Would you like to ask Magic 8 Ball another question (enter 'y' for yes, 'n' for no)? ")
    let playAgain = readLine()!
    if playAgain == "y" {
        keepPlaying = true
    } else {
        keepPlaying = false
        print("Goodbye :)")
    }
} // end while-loop