Print subview on top of image picker

🎤 General Discussion Swift
1

My code takes a photo using image Picker and places it on a imageview. The problem is that the subview on the image picker is not being transferred. How can I transfer the subview on top of the image taken.

     @IBAction func takePhoto(_ sender: UIButton) {
    imagePicker =  UIImagePickerController()
    imagePicker.delegate = self
    imagePicker.sourceType = .camera
    present(imagePicker, animated: true, completion: nil)
    let mainView = UIView.init(frame: CGRect.init(x: 0, y: 0, width: self.view.frame.size.width, height: self.view.frame.size.height-150))

    let frame  = CGRect.init(x: 0, y: 0, width: self.view.frame.size.width, height: 120)
    let blockView = UIImageView.init(frame: frame)
    blockView.contentMode = .scaleAspectFit
    blockView.image   = UIImage(named: "f")


    mainView.addSubview(blockView)

    imagePicker.cameraOverlayView = mainView

}