How do you get the width and height of a `UIView` who's size and position are set using Auto Layout and Apple's Visual Format Language?

Here's the code (`view` is just the variable from `UIViewController`):

```
// Create and add the view
var stageView = UIView()
stageView.setTranslatesAutoresizingMaskIntoConstraints(false) // Since I'm using Auto Layout I turn this off
view.addSubview(stageView)

// Create and add constraints to the containing view
let viewsDictionary = ["stageView":stageView]
let horizontalConstraints: NSArray = NSLayoutConstraint.constraintsWithVisualFormat("H:|-150-[stageView]-150-|", options: NSLayoutFormatOptions(0), metrics: nil, views: viewsDictionary)
let verticalConstraints: NSArray = NSLayoutConstraint.constraintsWithVisualFormat("V:|-100-[stageView]-150-|", options: NSLayoutFormatOptions.AlignAllCenterX, metrics: nil, views: viewsDictionary)
view.addConstraints(horizontalConstraints)
view.addConstraints(verticalConstraints)        
println("stageView.frame=\(stageView.frame)")

```

and got:

```
stageView.frame=(0.0,0.0,0.0,0.0)

```

so I tried:

```
let fittingSize = stageView.systemLayoutSizeFittingSize(UILayoutFittingCompressedSize)
println("fittingSize=\(fittingSize)")

```

and got:

```
fittingSize=(0.0,0.0)

```

I can't seem to find a way to get the size. I'm able to add subviews to `stageView` that place just fine using Auto Layout and Visual Format Language, but I can't get width and height for `stageView` which I need to further position those subviews.

Any ideas?