Create shadow around a UIVisualEffectView without covering the whole view

Ok, so the problem was that my background in the underlying view was white. And with the UIBlurEffect .extraLight used on a background which is lighter than the BlurEffect the shadow beneath a UIVisualView appears darker than with a more vivid background.

Also described in this question:
Fix UIVisualEffectView extra light blur being gray on white background

UPDATE

I found a project explaining how to solve this on Github The solution involves creating a 9-part UIImage to represent the shadow. The creator also explains the underlying layers of the iOS 10 Maps.

So i'm trying to recreate the look of iOS 10 maps. I decided to attach the maps app in the simulator to the debugger to see what was going on...

Apple actually get around this by having a UIImage over the top of the content with the border and shadow. Not the most elegant way to do it but i'm going for the exact look so I'm going to take the exact approach.

I also grabbed the asset (using this) from the Maps app to save making your own one. Shame they only have @2x artwork in it though :/

I found in iOS 12, this is not a problem, the UIVisualEffectView ignore the shadow of underneath views, it just sees through the shadow, like the shadow not exist.