Test for optionals

optionals.swift

extension Dictionary {
    func test() {
        for (key,value) in self {
            //Works
            if value is Int {
                println("int")
            }
            //Throws compiler error: cannot downcast from 'Value' to a more optional type 'Int?'
            if value is Int? {
                println("optional int")
            }
        }
    }
}

var dict: [String: Int] = ["four":4,"five":5]
var dictWithOptionals: [String: Int?] = ["four":4,"five":nil]
    
dict.test()
dictWithOptionals.test()