Class casting dynamically in swift

Question

I am trying to dyanmically cast to a class in Swift. Is this possible? Here is the code I am trying to use:

let stringClass: AnyClass = NSString.self
let anyObject: AnyObject = "foo"
let string = anyObject as! stringClass

The code fails to compile at the cast. Is this possible and if so, why is the right syntax?

Real use case

Here is the real issue. I am attempting to refactor this code:

switch (value) {
    case "valueOne":
        viewController = storyboard.instantiateViewController(withIdentifier: "foo") as! FirstViewController
    case "valueTwo":
        viewController = storyboard.instantiateViewController(withIdentifier: "bar") as! SecondViewController
    default:
        return nil
}

into:

let controllersDictionary: [String: (String, UIViewController.Type)] = [
    "valueOne" : ("bar", FirstViewController.self),
    "valueTwo" : ("foo", SecondViewController.self)
]
let tuple = controllersDictionary[value]!
let identifier = tuple.0
let cast = tuple.1
let viewController = storyboard.instantiateViewController(withIdentifier: identifier) as! cast

Answer 1

I'm not sure exactly what you're trying to achieve, but here's a working version of your example:

func cast<T>(value: Any, to type: T) -> T? {
    return castedValue as? T
}

let inputValue: Any = "this is a test"
let inputType = String.self()
let casted = cast(value: inputValue, to: inputType)

print(casted)