I've gotten pretty far today on this and I'm about to call it a day but it's KILLING ME that I can't figure out how to get a small border around my image in my DetailViewController after passing the asset through from the ViewController.

if let pushedFlagImage = selectedFlag {
            imageView.image = UIImage(named: pushedFlagImage)
            imageView.layer.borderWidth = 0.5
            imageView.layer.borderColor = UIColor.black.cgColor
        }
    }

it feels like I've tried every permutation of imageView.layer. If the imageView didn't take up the whole screen the border covers and entire outside of the bound of the UIImageView but not the actual photo.

Any tips?

Set the aspect ratio of imageView to 2:1 in your storyboard should solve your problem. To do it, control drag your imageView to its self or click the "add to new constraints" icon in storyboard, it is a little square icon at the bottom.

The problem here is your imageView's aspect ratio is not aligned with your flag image's aspect ratio. As your countries flas image is all 2:1, 600 300 or 400 200.

Otherwize you could set a fix imageView height in storyboard like 200 or 300 per flag images you are using.