/ Swift

Swift enum all values

In this quick tutorial I'll show you how to get all the possible values for a Swift enum type with a generic solution written in Swift 4.

First we need to define a new EnumCollection protocol, and then we'll make a protocol extension on it, so you don't have to write too much code at all.

public protocol EnumCollection: Hashable {
    static func cases() -> AnySequence<Self>
    static var allValues: [Self] { get }
}

public extension EnumCollection {
    
    public static func cases() -> AnySequence<Self> {
        return AnySequence { () -> AnyIterator<Self> in
            var raw = 0
            return AnyIterator {
                let current: Self = withUnsafePointer(to: &raw) { $0.withMemoryRebound(to: self, capacity: 1) { $0.pointee } }
                guard current.hashValue == raw else {
                    return nil
                }
                raw += 1
                return current
            }
        }
    }
    
    public static var allValues: [Self] {
        return Array(self.cases())
    }
}

From now on you only have to conform your enum types to the EnumCollection protocol and you can enjoy the brand new cases method and allValues property which will contain all the possible values for that given enumeration.

enum Weekdays: String, EnumCollection {
    case sunday, monday, tuesday, wednesday, thursday, friday, saturday
}

for weekday in Weekdays.cases() {
    print(weekday.rawValue)
}

print(Weekdays.allValues.map { $0.rawValue.capitalized })

Note that the base type of the enumeration needs to be Hashable, but that's not a big deal. This solution is part of the CoreKit framework and it works like a charm.

External sources