What is the difference between classes and structures in Swift?

Classes are reference types, structures are value types.

Main differences:

• Inheritance: Classes support inheritance, structures do not.
• Type Casting: Allows checking and interpreting the type of an instance at runtime.
• Deinitialization: Classes have deinitializers (deinit) for resource cleanup, structures do not.
• Reference Counting: Classes use automatic reference counting (ARC) for memory management. Structures are copied upon passing or assignment (copy-on-write can be used for optimization).
• Mutating methods: Methods that modify the properties of a structure or enumeration instance must be marked with the mutating keyword. This is not required for classes.

Example of creation:

// Structure
struct Point {
    var x: Int
    var y: Int
}

// Class
class Circle {
    var radius: Double
    var center: Point

    init(radius: Double, center: Point) {
        self.radius = radius
        self.center = center

    }
}

Example of behavior during assignment:

// Structure
var point1 = Point(x: 1, y: 2)
var point2 = point1 // Creates a copy
point2.x = 10

print(point1.x) // Output: 1

// Class
var circle1 = Circle(radius: 5.0, center: Point(x: 0, y: 0))
var circle2 = circle1 // Reference assignment occurs
circle2.radius = 10.0

print(circle1.radius) // Output: 10.0