I have started subject project and I am not seeing the red background as mentioned on page 457.

It appears this won't affect the rest of the app, but I wanted to understand what this difference is. I'm using XCode 11.4.1 and macOS Catalina 10.15.4

Here's the code:

override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        imageView = NSImageView(image: NSImage(named: "penguin")!)
        imageView.translatesAutoresizingMaskIntoConstraints = false
        imageView.frame = CGRect(x: 272, y: 172, width: 256, height: 256)
        view.addSubview(imageView)
        // According to the book, this should create a red background, but it does not.
        imageView.layer?.backgroundColor = NSColor.red.cgColor
        let button = NSButton(title: "Click Me", target: self, action: #selector(animate))
        button.frame = CGRect(x: 10, y: 10, width: 100, height: 30)
        view.addSubview(button)
    }

It works if I force it using the imageView.wantsLayer = true before the background color line.

Tom