Check the corner radius of an iPhone / iPad display.

Adds a displayCornerRadius property to UIScreen, which reads the private _displayCornerRadius. The selector somewhat obscured, which usually means it will get past app review. However, use at your own risk!

I didn't want to use model identifiers (i.e., iPhone10,2) and miss an international variant, or have to update it when new devices launch.

It's also tricky to use screen resolutions, as multiple devices share the same resolution and scale with different corner radii. Display Zoom messes with this too, and ultimately it just seems like a bad idea to assume anything about the device based on the display resolution.

iOS device displays use a continious corner curve, which means the corners are not true circles. In iOS 13+ you can use CALayer.cornerCurve to specify a continuous corner curve. You might create a view subclass like this:

class DisplayCornerMatchingView: UIView {
    override func layoutSubviews()
        super.layoutSubviews()
        layer.cornerCurve = .continuous
        layer.cornerRadius = window?.screen.displayCornerRadius ?? 0
    }
}

Or perhaps you want to animate from a different corner radius to the screen one. Either way, be sure to set layer.cornerCurve = .continuous on the view.

On iOS 14.1, the follow values were reported for each device with rounded corners: