为Blurred ModalView添加插入/边距？

Question

我正在尝试打开一个背景模糊的ModalView（但周围有一些空间）

为什么这段代码会忽略inset / frame命令？我可以看到模糊的图像。但它是全屏的。

PS：此VC通过Storyboard分配

class InfoViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        self.setupView()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    func setupView() {

        // Add some space around the view
        self.view.clipsToBounds = true
        self.view.frame = UIEdgeInsetsInsetRect(self.view.frame, UIEdgeInsetsMake(20, 10, 10, 10)) // <-- not working?

        // Take screenshot from parent VC
        let parentVC : UIViewController = self.presentingViewController
        UIGraphicsBeginImageContext(parentVC.view.bounds.size)
        parentVC.view.drawViewHierarchyInRect(parentVC.view.bounds, afterScreenUpdates:true)
        var image:UIImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        // Blur screnshot
        image = image.applyBlurWithRadius(20, tintColor: UIColor(white: 1.0, alpha: 0.2), saturationDeltaFactor: 1.3, maskImage: nil)

        // Add screenshot to view
        let backgroundImageView : UIImageView = UIImageView(image:image)
        self.view.addSubview(backgroundImageView)
    }
}