Screen mirror not behaving as expected (Swift)

Question

I'm trying to implement some simple screen mirroring in my swift application but I'm getting undesired behavior. When my code executes, the external display gets the phone view but the iphone screen goes black. Also in the external view it's filled in with black. Here's a screenshot:

Here's my code to setup the external view:

func initializeExternalScreen(external: UIScreen){
    self.mirroredScreen = external;

    // Find max resolution
    var max = CGSize()
    var maxScreenMode = UIScreenMode()

    for current in self.mirroredScreen.availableModes {
        if (current.size.height > max.height || current.size.width > max.width) {
            max = current.size;
            maxScreenMode = current;
        }
    }

    self.mirroredScreen.currentMode = maxScreenMode;
    self.mirroredWindow = UIWindow(frame: self.mirroredScreen.bounds)
    self.mirroredWindow.hidden = false
    self.mirroredWindow.layer.contentsGravity = kCAGravityResizeAspect
    self.mirroredWindow.screen = self.mirroredScreen
    self.mirroredScreenView = UIView(frame: self.mirroredScreen.bounds)
    self.mirroredScreenView.addSubview(self.view)
    self.mirroredWindow.addSubview(self.mirroredScreenView)


}

Any ideas?