Classes in Swift

Classes behave mostly the same as classes in JS or Ruby.

• Use class keyword
• Assign class properties within the block using let or var
• Use init for initialize, deinit for any cleanup
• Use func keyword for class methods
• Use self to access class instances
• Use the override keyword to override methods on the parent class

class Car {
  let name: String
  let year: Double
  var mpg: Float

  init(name: String, year: Double, mpg: Float) {
    self.name = name
    self.year = year
    self.mpg = mpg
  }

  func simpleDescription() -> String {
        return "This car mpg is \(self.mpg) miles per gallon"
    }

}

let volvo = Car(name: "xc60", year: 2023, mpg: 31.2)

print(volvo.name)
volvo.mpg = 30.0
print(volvo.simpleDescription())

You can also do OOP-ish class inheritence, by using the : operator, like a typedef.

class Vehicle {
  let wheels: Double
  init(wheels: Double) {
    self.wheels = wheels
  }

  func simpleDescription() -> String {
    return "This is a vehicle with \(self.wheels) wheels on it"
  }

}

class Car: Vehicle {
  let name: String
  let year: Double
  var mpg: Float

  init(name: String, year: Double, mpg: Float) {
    self.name = name
    self.year = year
    self.mpg = mpg
    super.init(wheels: 4)
  }

  override func simpleDescription() -> String {
        return "This car mpg is \(self.mpg) miles per gallon"
    }

}

let volvo = Car(name: "xc60", year: 2023, mpg: 31.2)

print(volvo.name)
volvo.mpg = 30.0
print(volvo.simpleDescription())

Other things about classes:

• Class properties have getters and setters, as well as willSet and willGet hooks-like things.
• Class properties can be public and private, and static. Same same.