按钮无法渲染

Question

class SwiftyRecordButton: SwiftyCamButton {

    private var circleBorder: CALayer!
    private var innerCircle: UIView!

    override init(frame: CGRect) {
        super.init(frame: frame)
        drawButton()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        drawButton()
    }

    private func drawButton() {
        self.backgroundColor = UIColor.white
        circleBorder = CALayer()
        circleBorder.backgroundColor = UIColor.red.cgColor
        circleBorder.borderWidth = 6.0
        circleBorder.borderColor = UIColor.blue.cgColor
        circleBorder.bounds = self.bounds
        circleBorder.position = CGPoint(x: self.bounds.midX, y: self.bounds.midY)
        circleBorder.cornerRadius = self.frame.size.width / 2
        layer.insertSublayer(circleBorder, at: 0)
    }
}

我在渲染此按钮时遇到问题。这是一个特殊的按钮，我用来代替来自swifty cams库的标准按钮。问题来自drawButton函数。即使我清楚地称之为它，我也看不到带有边框的Snapchat样式按钮。谁能看到我哪里出错？