Title: Swift Protocol Extensions

In Swift, protocol extensions are a powerful feature that allows you to provide default implementations for methods, properties, and other requirements defined in a protocol. This enables you to easily add functionality to types that conform to the protocol without modifying their code. Protocol extensions are particularly useful when you want to extend the capabilities of existing types or when you have multiple types that share common behavior defined by a protocol.

Here's an example to illustrate the usage of protocol extensions:

protocol Drawable {
    func draw()
}

extension Drawable {
    func draw() {
        print("Implement drawing logic here")
    }
}

struct Circle: Drawable {
    // No need to provide an implementation for `draw` as the default implementation from the protocol extension will be used
}

struct Rectangle: Drawable {
    func draw() {
        print("Custom drawing logic for Rectangle")
    }
}

In the above code, we have defined a protocol named `Drawable` with one method requirement `draw()`. We then provide a default implementation for this method using a protocol extension. The default implementation simply prints a generic message.

The `Circle` struct conforms to the `Drawable` protocol but does not provide its own implementation for `draw()`. As a result, it will automatically use the default implementation provided by the protocol extension.

On the other hand, the `Rectangle` struct does provide its own implementation for `draw()`, which overrides the default implementation from the protocol extension. When an instance of `Rectangle` is called to `draw()`, it will print the custom message specified in its implementation.

By using protocol extensions, you can define default behavior for methods and properties that can be shared across multiple types. This makes it easier to reuse and extend functionality in a more modular and maintainable way.

Summary: Protocol extensions in Swift allow you to provide default implementations for methods, properties, and other requirements defined in protocols. They enable you to extend the functionality of types that conform to the protocol without modifying their code.