You can add that new subview to your application window.
func attach(sender : UIButton)
{
// Calculate and replace the frame according to your keyboard frame
var customView = UIView(frame: CGRect(x: 0, y: self.view.frame.size.height-300, width: self.view.frame.size.width, height: 300))
customView.backgroundColor = UIColor.redColor()
customView.layer.zPosition = CGFloat(MAXFLOAT)
var windowCount = UIApplication.sharedApplication().windows.count
UIApplication.sharedApplication().windows[windowCount-1].addSubview(customView);
}