Swift 自定义图形没有'；今天不能显示分机

我在今天的扩展中取得了进步。我为它创建了额外的类。借助

IBDesignable

，我可以在故事板中看到它。但circle并没有出现在现实设备（iPhone5s、iPad3）或模拟器的今日扩展中。我怎样才能修好它

    import UIKit

@IBDesignable
class CPUView: UIView {

    // MARK: - colors
    @IBInspectable var firstColor: UIColor = UIColor.blackColor()
    @IBInspectable var secondColor: UIColor = UIColor.greenColor()
    @IBInspectable var thirdColor: UIColor = UIColor.yellowColor()

    // Only override drawRect: if you perform custom drawing.
    // An empty implementation adversely affects performance during animation.
    override func drawRect(rect: CGRect) {
        // Drawing code
        self.addCircle(10, capRadius: 0.0)
    }

    func addOval(lineWidth: CGFloat, path: CGPath, strokeColor: UIColor, fillColor: UIColor, strokeStart: CGFloat, strokeEnd: CGFloat) {
        let shape = CAShapeLayer()
        shape.lineWidth = lineWidth
        shape.path = path
        shape.strokeColor = strokeColor.CGColor
        shape.fillColor = fillColor.CGColor
        shape.strokeStart = strokeStart
        shape.strokeEnd = strokeEnd
        layer.addSublayer(shape)
    }

    func addCircle(arcRadius: CGFloat, capRadius: CGFloat) {
        let X = CGRectGetMidX(self.bounds)
        let Y = CGRectGetMidY(self.bounds)

        let firstPathCircle = UIBezierPath(ovalInRect: CGRectMake(X - arcRadius/2, Y - arcRadius/2, arcRadius, arcRadius)).CGPath

        self.addOval(0.1, path: firstPathCircle, strokeColor: UIColor.redColor(), fillColor: UIColor.yellowColor(), strokeStart: 0.0, strokeEnd: 0.5)
    }

}

更新

我试图在

drawRect

中编写代码，但得到了相同的结果

 override func drawRect(rect: CGRect) {
    // Drawing code
    let x = CGRectGetMidX(self.bounds)
    let y = CGRectGetMidY(self.bounds)
    let radius = CGFloat()

    let path = UIBezierPath(ovalInRect: CGRectMake(x - radius/2, y - radius, 100, 100)).CGPath

    let shape = CAShapeLayer()
    shape.lineWidth = 0.0
    shape.fillColor = UIColor.greenColor().CGColor
    shape.path = path
    layer.addSublayer(shape)
}

---

我写了下面的代码，它对我很有用

override func viewDidLoad() {
        super.viewDidLoad()
        self.preferredContentSize = CGSize(width: self.view.frame.width, height: 200.0)
    }