struct Pt {
    let x: Int
    let y: Int
    init(_ x: Int, _ y: Int) {self.x = x; self.y = y}
    init(){self.init(0, 0)}
}

let p = Pt(2, 3)

func valueForKey(item : Any, key: String) -> Any? {
    let mirror = reflect(item)
    for index in 0..<mirror.count {
        let child = mirror[index]
        if key == child.0 {return child.1.value}
    }
    return nil
}

valueForKey(p, key: "x") // 2
valueForKey(p, key: "y") // 3
valueForKey(p, key: "z") // nil