Inheritance.swift

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

import UIKit

class Vehicle {
  var model: String!
  var tires = 4
  var currentSpeed: Double = 0
  init() {
    
  }
  
  func drive() {
    
  }
  
  func accelerate(_ speedIncrease: Double) { // super class method.
    currentSpeed += speedIncrease * 2
  }
  
  func stop() {
    
  }
}

class SportsCar: Vehicle {
  override init() {
    super.init()
    model = "Ferrari"
  }
  override func accelerate(_ speedIncrease: Double) {
    currentSpeed += speedIncrease * 5 // override the superclass method and increase the acceleration to 5 times the normal acceleration
  }
}

class Truck: Vehicle {
  override init() {
    super.init()
    model = "Tata Prima"
  }
  override func accelerate(_ speedIncrease: Double) {
    currentSpeed += speedIncrease // override the superclass method and reduce the acceleration
  }
}