enum-from-any.swift

import Foundation

enum Enum: Int {
    case one = 1
    case two = 2
}

func enumFromAny<T>(_ ctor: (Int) -> T?, _ v: Any) -> T? {
    if let n = v as? NSNumber {
        return ctor(n.intValue)
    } else {
        return nil
    }
}

func main() {
    let n = NSNumber(integerLiteral: 2)
    let a = n as Any
    if let e = enumFromAny(Enum.init, a) {
        print(e)
    } else {
        print("nil")
    }
}

main()