How to make Swift Enum conforms to Identifiable protocol

If you want to use Swift Enum in a List or ForEach, you need to make your enum conforms to Identifiable protocol.

In this article, we will explore how easy or hard it is to do it.

I will show you how to make two Enum types conform to the Identifiable protocol.

1. Enum without Associated Value.
2. Enum with Associated Value.

First, let's recap on what the Identifiable protocol is.

What is Identifiable protocol

Identifiable provide a way to uniquely identify things. The protocol required us to return anything that could do just that.

The return value must meet two criteria.

1. It must be named id with a generic type ID.
2. ID type must conform to the Hashable protocol.

public protocol Identifiable<ID> {
    // 2
    associatedtype ID : Hashable

    // 1
    var id: Self.ID { get }
}

In summary, we need our enum to present some unique Hashable value as an id.

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How to make Enum without Associated Value conforms to Identifiable protocol

By default, an enumeration without associated values gains Hashable conformance automatically.

So all you need to do are:

1. Make your enum conform to the Identifiable protocol.
2. Use the enum itself as the ID since it already conforms to Hashable.

Here we have a Direction enum.

enum Direction {
    case north
    case south
    case east
    case west
}

To make this enum conform to the Identifiable protocol. We add the Identifiable protocol and use self as the id.

enum Direction: Identifiable {
    // 1
    var id: Self {
        return self
    }
    
    case north
    case south
    case east
    case west
}

1 Self refer to Direction. Since an enum without associated value conforms to Hashable by default, we can use this as an ID type.

That's all we need to do for an enum without associated value.

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How to make Enum with Associated Value conforms to Identifiable protocol

For an enum with associated value, Swift doesn't automatically conform to the Hashable protocol for you.

Luckily, we only need to do a few extra steps to make it conforms to the Identifiable protocol.
We make an enum conforming to the hashable protocol.

1. First, we make an enum conforming to Hashable.
2. Then, we make it conforms to Identifiable.

Conforms to Hashable protocol

We can easily make an enum conforming to the Hashable protocol if our enum meets these criteria:

• All its associated values must conform to Hashable.
• Explicitly conform to Hashable in the declaration.

As an example, I create an enum with an associated value, Barcode.

enum Barcode {
    case basic(Int)
    case qrCode(String)
}

All associated values (Int and String) in Barcode conform to Hashable. So, the only step we need to do is to add Hashable conformance to our declaration.

enum Barcode: Hashable {
    case basic(Int)
    case qrCode(String)
}

That's all we need to do to make an enum conform to Hashable.

Conforms to Identifiable protocol

Once your enum conforms to the Hashable protocol, we can make it conforms Identifiable protocol the same way as Enum without Associated Value.

enum Barcode: Hashable, Identifiable {
    var id: Self {
        return self
    }
    
    case basic(Int)
    case qrCode(String)
}