Day 4; Class vs. Instance.swift

import Foundation

class Person {
    var age: Int = 0

    init(initialAge: Int) {
        if initialAge < 0 {
            self.age = 0
            print("Age is not valid, setting age to 0.")
        } else {
            self.age = initialAge
        }
    }

    func amIOld() {
        if age < 13 {
            print("You are young.")
        } else if age < 18 {
            print("You are a teenager.")
        } else {
            print("You are old.")
        }
    }

    func yearPasses() {
        self.age += 1
    }
}

let t = Int(readLine()!)!

for _ in 0..<t {
    let age = Int(readLine()!)!
    let p = Person(initialAge: age)

    p.amIOld()

    for i in 1...3 {
        p.yearPasses()
    }

    p.amIOld()

    print("")
}