Swift Inheritance
Building classes that inherit properties and methods from other classes
🧬 What is Inheritance?
Inheritance allows a class to inherit properties, methods, and characteristics from another class. The inheriting class is called a subclass, and the class being inherited from is the superclass.
// Base class (superclass)
class Animal {
var name: String
init(name: String) {
self.name = name
}
func makeSound() {
print("Some generic animal sound")
}
}
// Inherited class (subclass)
class Dog: Animal {
override func makeSound() {
print("Woof! Woof!")
}
}
let myDog = Dog(name: "Buddy")
myDog.makeSound() // Output: "Woof! Woof!"
Output:
Woof! Woof!
Key Inheritance Concepts
Superclass
The parent class that provides properties and methods
class Vehicle {
var speed: Int = 0
}Subclass
The child class that inherits from superclass
class Car: Vehicle {
var brand: String = ""
}Override
Modify inherited methods in subclass
override func start() {
print("Car started")
}Super
Call superclass methods from subclass
override func start() {
super.start()
}🔹 Basic Inheritance Example
Here's how to create a simple inheritance hierarchy:
// Superclass
class Shape {
var color: String
init(color: String) {
self.color = color
}
func describe() {
print("This is a \(color) shape")
}
}
// Subclass
class Circle: Shape {
var radius: Double
init(color: String, radius: Double) {
self.radius = radius
super.init(color: color)
}
override func describe() {
print("This is a \(color) circle with radius \(radius)")
}
}
let myCircle = Circle(color: "red", radius: 5.0)
myCircle.describe()Output:
This is a red circle with radius 5.0
🔹 Method Overriding
Subclasses can override methods from their superclass:
class Bird {
func fly() {
print("Bird is flying")
}
}
class Eagle: Bird {
override func fly() {
print("Eagle soars high in the sky")
}
}
class Penguin: Bird {
override func fly() {
print("Penguins can't fly, but they swim!")
}
}
let eagle = Eagle()
let penguin = Penguin()
eagle.fly() // Eagle soars high in the sky
penguin.fly() // Penguins can't fly, but they swim!Output:
Eagle soars high in the sky
Penguins can't fly, but they swim!