Understanding extensions

Sometimes, you need to provide extra capabilities to an object without modifying the object declaration. For this, we use extensions.

Here's what an extension looks like:

extension existingType : protocolName {
    property1
    property2
    property3
 
    method1()
    method2()
}

Let's look at how to work with extensions. You'll start by adopting a protocol via an extension.

Adopting a protocol via an extension

Let's make the Sauce enumeration conform to CalorieCountProtocol using extensions.

Add the following code after the declaration for Sauce:

// Sauce enum
enum Sauce {
    case chili
    case tomato
}

// Sauce adopting CalorieCountProtocol via extension
extension Sauce : CalorieCountProtocol...