Inheritance in Swift

Introduction

In Swift, inheritance is a fundamental concept of Object-Oriented Programming that allows one class (called the subclass or child class) to acquire properties and methods from another class (called the superclass or parent class). This mechanism promotes code reusability and hierarchical classifications.

A subclass can extend or override functionalities of the superclass, enabling specialized behaviors without rewriting the existing code. Inheritance also supports method overriding, where the subclass provides a specific implementation of a method defined in its superclass.

Key Points to Remember

The class that inherits properties and methods is called the subclass, while the class being inherited from is the superclass.
A subclass can override methods and properties of its superclass using the override keyword.
Swift does not support multiple inheritance, meaning a class can inherit from only one superclass.
Subclasses can add new properties and methods in addition to what they inherit.
Initializers can be overridden in the subclass to customize object creation.

Syntax

class Superclass {
     // Properties and methods
}

class Subclass: Superclass {
     // Additional properties and methods
     // Overridden properties and methods
}

Example 1: Inheriting Properties and Methods

Let's demonstrate how a subclass inherits properties and methods from a superclass in Swift.

import Foundation

class Vehicle {
     var brand: String

     init(brand: String) {
         self.brand = brand
    }

     func honk() {
         print("Beep! Beep!")
    }
}

class Car: Vehicle {
     var model: String

     init(brand: String, model: String) {
         self.model = model
         super.init(brand: brand)
    }

     func displayDetails() {
         print("Brand: \(brand), Model: \(model)")
    }
}

let car1 = Car(brand: "Toyota", model: "Corolla")
car1.honk()
car1.displayDetails()

Output

Beep! Beep!
Brand: Toyota, Model: Corolla

Example 2: Overriding Methods in Subclass

In this example, we will see how a subclass can override a method of its superclass to provide specific behavior.

import Foundation

class Animal {
     func sound() {
         print("Animal makes a sound")
    }
}

class Dog: Animal {
     override func sound() {
         print("Dog barks")
    }
}

let myDog = Dog()
myDog.sound()

Output

Dog barks