I'm having trouble with understanding how to properly do unwrapping in Swift. Here is the situation:

I have these two classes:

class Alpha
{
  var val: Int

  init(x: Int)
  {
    val = x
  } 

  func doSomething() -> Int
  {
    // does stuff and returns an Int value
    return val
  }
}

and a second class which is a subclass of the first

class Beta: Alpha
{
  var str: [String] = []

  override init(x: Int)
  {
    super.init(x)
  }

  func doSomething() -> String
  {
    // does stuff and returns a String
    return str
  }
}

So far so good, these two classes work as expected. But now I want to create a dictionary to store several of both these class objects. So I've created a class to manage the dictionary and add items to it.

class Gamma
{
  var myDict: [String:AnyObject] = [:]

  func addAlphaToDict(key: String, val: Int)
  {
    self.myDict[key] = Alpha(x: val).self
  }

  func addBetaToDict(key: String, val: Int)
  {
    self.myDict[key] = Beta(x: val).self
  }
}

This also is working, but I think this could somehow be improved. The issue I'm having is now when I try to access values in the dictionary:

var foo = Gamma()

foo.addAlphaToDict(key: "blah", val: 45)
foo.addBetaToDict(key: "bluh", val: 23)

var result1 = (foo.myDict["blah"] as! Alpha).doSomething()

var result2 = (foo.myDict["bluh"] as! Beta).doSomething()

I find that the syntax here is very clunky and I feel like I'm doing it wrong, even though it works. I'm an experienced developer, but have only just started using Swift so I'm not really sure about certain things. Could someone with more Swift experience show me how to improve this code, or point me in the direction I should be going? Thanks!