Title: "Swift Option Sets for Type-Safe Value Combinations

A portrait painting style image of a pirate holding an iPhone.

by The Captain

April 7, 2024

Working with Option Sets in Swift

Option sets in Swift provide a way to work with combinations of values in a type-safe manner. They are particularly useful when you need to represent a set of related options that can be independently turned on or off.

Let's say you have a set of permissions for a user, such as read, write, and delete. You can create an option set to represent these permissions as follows:

struct Permissions: OptionSet {
    let rawValue: Int

    static let read = Permissions(rawValue: 1 << 0)
    static let write = Permissions(rawValue: 1 << 1)
    static let delete = Permissions(rawValue: 1 << 2)

In the above code snippet, we define a struct `Permissions` that conforms to the `OptionSet` protocol. We then define three static properties `read`, `write`, and `delete`, each representing a different permission with a unique raw value.

Using option sets allows you to easily combine these permissions using bitwise operations:

var userPermissions: Permissions = [.read, .write] // User can read and write

if userPermissions.contains(.read) {
    print("User has read permission")

if userPermissions.contains(.write) {
    print("User has write permission")

In this code snippet, we create a variable `userPermissions` that combines the read and write permissions. We then use the `contains` method to check if the user has a specific permission.

Option sets provide a convenient way to work with sets of related options in Swift and make your code more expressive and type-safe. They are especially useful when dealing with scenarios where you need to represent combinations of values that can be independently toggled.