Swift init from unknown class

gistfile1.swift

import Cocoa

protocol Thing {
	var x: String {get}
	init(s: String)
}

class Foo: Thing {

	let x: String

	required init(s: String) {
		x = s
	}
}

class Bar: Thing {

	let x: String

	required init(s: String) {
		x = s
	}
}

func classToUse() -> Thing.Type {

	return Foo.self //maybe it's Bar sometimes.
}

let someClass = classToUse()
let something = someClass.init(s:"A string")
something.x

// Works now! The answer was the init call.
// See David Owens II’s gist: https://gist.github.com/owensd/bfe4ff8e17bbf6db842c