Trying to get a Singleton class going in Swift. I'm not getting any errors, but its also just plain not working properly.

Here's the code:

// The Singleton class:
class DataWarehouse {
    class var sharedData:DataWarehouse {
        struct Static {
            static var onceToken : dispatch_once_t = 0
            static var instance : DataWarehouse? = nil
        }
        dispatch_once(&Static.onceToken) {
            Static.instance = DataWarehouse()
        }
        return Static.instance!
    }

    // Here's a variable that I want to pass around to other classes:
    var x = 10 

}

Next, I created two classes that can access the value of x and use it, change its value, etc:

class ClassA {

    var theData = DataWarehouse()

    func changeX() {
        // First, log out the current value of X:
        println("ClassA ==> x is currently: \(theData.x)")

        // Next, change it:
        theData.x = -50
        println("ClassA ==> x was just set to: \(theData.x)")
    }

}

Here's the second class - its basically the same as ClassA:

class ClassB {

    var theData = DataWarehouse()

    func changeX() {
        // First, log out the current value of X:
        println("ClassB ==> x is currently: \(theData.x)")

        // Next, change it:
        theData.x = -88
        println("ClassB ==> x was just set to: \(theData.x)")
    }

}

Finally, in main.swift I put the whole thing together:

let objectA = ClassA()
objectA.changeX()

let objectB = ClassB()
objectB.changeX()

The output I get is:

ClassA ==> x is currently: 10
ClassA ==> just set x to: -50
ClassB ==> x is currently: 10
ClassB ==> just set x to: -88

So the value of x doesn't truly get updated, its always 10.

What am I doing wrong?