In Swift, is it possible to convert a string to an enum?

Question

If I have an enum with the cases a,b,c,d is it possible for me to cast the string \"a\" as the enum?

Answer 1

In case with an enum with Int type you can do it so:

enum MenuItem: Int {
    case One = 0, Two, Three, Four, Five //... as much as needs

    static func enumFromString(string:String) -> MenuItem? {
        var i = 0
        while let item = MenuItem(rawValue: i) {
            if String(item) == string { return item }
            i += 1
        }
        return nil
    }
}

And use:

let string = "Two"
if let item = MenuItem.enumFromString(string) {
    //in this case item = 1 
    //your code
} 

Answer 2

Riffing on djruss70's answer to create highly generalized solution:

extension CaseIterable {
    static func from(string: String) -> Self? {
        return Self.allCases.first { string == "\($0)" }
    }
    func toString() -> String { "\(self)" }
}

Usage:

enum Chassis: CaseIterable {
    case pieridae, oovidae
}

let chassis: Chassis = Chassis.from(string: "oovidae")!
let string: String = chassis.toString()

Note: this will unfortunately not work if the enum is declared @objc. As far as I know as of Swift 5.3 there is no way to get this to work with @objc enum's except brute force solutions (a switch statement).

If someone happens to know of a way to make this work for @objc enums, I'd be very interested in the answer.