What does the CaseIterable protocol do?

Sources & Resources

Main Source: 🔗 Ace the iOS Interview

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TL/DR

As the name suggests,CaseIterable is a protocol that provides a handy way of iterating through all of the individual cases in an enum.

When using an enum that conforms to CaseIterable,you can access a collection of all of the enum’s cases by using the allCases property:

enum CompassDirection: CaseIterable {
    case north, south, east, west
}

// "There are 4 directions."
print("There are \(CompassDirection.allCases.count) directions.")

let caseList = CompassDirection.allCases.map({ "\($ 0 )" })
                    .joined(separator: ", ")
                    //"north, south, east, west"
print(caseList)

allCases provides the cases in the order of their declaration.

If your enum does not contain any associated values or availability attributes, Swift will automatically synthesize conformance to the CaseIterable protocol for you.