inheritance_parent_01.swift

class Person {
  let name: String
  var age: Int
  
  init(name: String, age: Int) {
    self.name = name
    self.age = age
  }
  func celebrateBirthday() {
    self.age += 1
    print("Happy Birthday \(self.name)")
  }
}

class Youtuber: Person {
  let channelName: String
  var subscribers: Int
  
  //we need to pass in the name & age of the Youtuber Person
  init(channelName: String, subscribers: Int, name: String, age: Int) {
    self.channelName = channelName
    self.subscribers = subscribers
    
    //we use this to initialise the Person from within the subclass
    super.init(name: String, age: Int)
  }
}