How to add a blur mask with a custom shape above a dynamic camera view in Swift?

Question

I am using Swift to develop an iOS application with a camera feature, and it requires a blur layer above the camera view with a hole in the middle like the image shown below.

Answer 1

I've done this by creating an overlay with a layer with said blurred image, and then using a mask that is built from a path that goes all the way around the extents, and then jumps to the cutout hole, going the opposite direction with the winding fill rule.

Refer to documetation here:

https://developer.apple.com/library/ios/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_paths/dq_paths.html

There are many documented examples of this though, here is one: drawing with clear color on UIView (cutting a hole) in static method