Playing around with enums in Swift

LivingForTheWeekend.swift

//: Playground - noun: a place where people can play

import UIKit

enum Day: Int {
    case Monday = 0, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday
    
    func checkDay() -> String {
        switch self.rawValue {
        case 0:
            return "The day is Monday"
        case 1:
            return "The day is Tuesday"
        case 2:
            return "The day is Wednesday"
        case 3:
            return "The day is Thursday"
        case 4:
            return "The day is Friday"
        case 5:
            return "The day is Saturday"
        case 6:
            return "The day is Sunday"
        default:
            return "There's only 7 days in a week"
        }
    }
    
    mutating func next() -> Void {
        if let nextDay = Day(rawValue: (self.rawValue + 1)) {
            self = nextDay
        } else {
            self = Day.Monday
        }
    }
    mutating func prev() -> Void {
        if let prevDay = Day(rawValue: (self.rawValue - 1)) {
            self = prevDay
        } else {
            self = Day.Sunday
        }
    }
    
}

var today = Day.Thursday

today.checkDay()

today.next()
today.checkDay()

today.prev()
today.checkDay()

protocol LivesByDay {
    func onThisDay(Day) -> String
}

class Artist {
    let topSong: String
    let sneakers: String
    
    init(topSong: String, sneakers: String) {
        self.topSong = topSong
        self.sneakers = sneakers
    }
}

class CraigDavid: Artist, LivesByDay {
    
    func onThisDay(day: Day) -> String {
        switch day {
        case .Monday:
            return "Meeting this girl"
        case .Tuesday:
            return "Taking her for a drink"
        case .Wednesday:
            return "Making love"
        case .Thursday:
            return "Making love"
        case .Friday:
            return "Making love"
        case .Saturday:
            return "Making love"
        case .Sunday:
            return "Chilling"
        }
    }
    
}

class HardFi: Artist, LivesByDay {
    
    func onThisDay(day: Day) -> String {
        switch day.rawValue {
        case 4, 5:
            return "Going out tonight, going out tonight"
        default:
            return "Living for the weekend"
        }
    }
    
}

class God: LivesByDay {
    
    func onThisDay(day: Day) -> String {
        switch day {
        case .Monday:
            return "Creating the heavens and the earth"
        case .Tuesday:
            return "Creating the sky"
        case .Wednesday:
            return "Creating dry land"
        case .Thursday:
            return "Creating the stars and heavenly bodies"
        case .Friday:
            return "Creating all that lives in water"
        case .Saturday:
            return "Creating all that lives on dry land"
        case .Sunday:
            return "Resting"
        }
    }
    
}

let craig = CraigDavid(topSong: "7 days", sneakers: "White")
craig.onThisDay(today)

let hardfi = HardFi(topSong: "Living for the Weekend", sneakers: "Adidas")
hardfi.onThisDay(today)

let jehovah = God()
jehovah.onThisDay(today)

func dailyActivity(var day: Day, person: LivesByDay) {
    for _ in 1...7 {
        person.onThisDay(day)
        day.next()
    }
}

dailyActivity(today, jehovah)