gistfile1.swift

// Playground - noun: a place where people can play

//Dynamic Casting in Swift
//http://blog.segiddins.me/2015/01/25/dynamic-casting-in-swift/

let json: NSDictionary = ["count":123,"name":"foobar"]

func id<U>(object: AnyObject?) -> U? {
    if let typed = object as? U {
        return typed
    }
    return nil
}

func doubleMaybe(i: Int?) -> Int? {
    if let i = i {
        return i * 2
    }
    
    return nil
}

let count1 = json["count"] as? Int
let doubleCount1 = doubleMaybe(count1)

let doubleCount2 = doubleMaybe(id(json["count"]))