iOS Dim background when a view is shown

Question

In my main view, I do some gesture action causing some new view to be shown. At this time I want to dim the entire background (except this new view) as a good UI practice. I

Answer 1

The above two answers work if the new view has it's own 'background', i.e. has no transparency. The problem that led me here cannot be solved that way though, what I was trying to do is this: I'm running an AVCaptureSession on my screen with the usual AVCaptureVideoPreviewLayer to display video in real time. I want to select a part of the screen (to later do something with only this part), and when this part is selected want to dim the rest of the video preview. This is what it looks like:

This is how I solved this: A new view is created depending on where the screen is touched and added as a subview of the video preview view. Then, I create 4 additional, non-overlapping rectangular subviews with the before-mentioned background color and opacity to cover the rest of the screen. I explicitly need all these views not to be subviews of the main view, because I need the ability to touch the screen somewhere else and change the selected area.

I'm sure there are more elegant ways to solve this, so if someone knows how please comment...