CALayer未在

Question

我正在尝试在视图中添加CALayer，显示了图层，但隐藏了文本。  我的代码如下：

let label = UILabel(frame: CGRect(x: 100, y: 100, width: 25, height: 25))
        label.text = "5"
        label.font = .boldSystemFont(ofSize: 10)
        label.adjustsFontSizeToFitWidth = true
        label.textColor = #colorLiteral(red: 0.4392156899, green: 0.01176470611, blue: 0.1921568662, alpha: 1)
        label.textAlignment = .center
        let sublayer = label.layer
        sublayer.backgroundColor = UIColor.yellow.cgColor
        sublayer.borderColor = UIColor.red.cgColor
        self.view.layer.addSublayer(sublayer)

能否让我知道我要去哪里错了？

谢谢