I found an error in the last edition of hackingWithmacOS, SwiftUI version on project 11.

// 4: create a label node with the current number, in nice, bright text
    let label = SKLabelNode(fontNamed: "HelveticaNeue-Light")
    label.text = bubble.name
    label.color = NSColor.white
    label.fontSize = 64

The label.color don't change the text color you may use this code.

        // 4. create a label node with the current number
        let label = SKLabelNode(fontNamed: "HelveticaNeue-Light")
        label.text = bubble.name
        label.fontColor = .white
        label.fontSize = 64