以编程方式定制的UITabBar

Question

我正在尝试以编程方式为UITabBar绘制形状。下面是代码

class CustomTabBar: UITabBar {
    private var shapeLayer: CALayer?

    private func addShape() {
        let shapeLayer = CAShapeLayer()
        shapeLayer.path = createPath()
        shapeLayer.strokeColor = UIColor.lightGray.cgColor
        shapeLayer.fillColor = UIColor.white.cgColor
        shapeLayer.lineWidth = 1.0

        if let oldShapeLayer = self.shapeLayer {
            self.layer.replaceSublayer(oldShapeLayer, with: shapeLayer)
        } else {
            self.layer.insertSublayer(shapeLayer, at: 0)
        }

        self.shapeLayer = shapeLayer
    }

    override func draw(_ rect: CGRect) {
        self.addShape()
    }

    init() {
        super.init(frame: .zero)
        self.addShape()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        fatalError("init(coder:) has not been implemented")
    }

    func createPath() -> CGPath {

        let height: CGFloat = 37.0
        let path = UIBezierPath()
        let centerWidth = self.frame.width / 2

        path.move(to: CGPoint(x: 0, y: 0)) // start top left
        path.addLine(to: CGPoint(x: (centerWidth - height * 2), y: 0)) // the beginning of the trough
        // first curve down
        path.addCurve(to: CGPoint(x: centerWidth, y: height),
                      controlPoint1: CGPoint(x: (centerWidth - 30), y: 0), controlPoint2: CGPoint(x: centerWidth - 35, y: height))
        // second curve up
        path.addCurve(to: CGPoint(x: (centerWidth + height * 2), y: 0),
                      controlPoint1: CGPoint(x: centerWidth + 35, y: height), controlPoint2: CGPoint(x: (centerWidth + 30), y: 0))

        // complete the rect
        path.addLine(to: CGPoint(x: self.frame.width, y: 0))
        path.addLine(to: CGPoint(x: self.frame.width, y: self.frame.height))
        path.addLine(to: CGPoint(x: 0, y: self.frame.height))
        path.close()

        return path.cgPath
    }

    override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
        let buttonRadius: CGFloat = 35
        return abs(self.center.x - point.x) > buttonRadius || abs(point.y) > buttonRadius
    }

    func createPathCircle() -> CGPath {

        let radius: CGFloat = 37.0
        let path = UIBezierPath()
        let centerWidth = self.frame.width / 2

        path.move(to: CGPoint(x: 0, y: 0))
        path.addLine(to: CGPoint(x: (centerWidth - radius * 2), y: 0))
        path.addArc(withCenter: CGPoint(x: centerWidth, y: 0), radius: radius, startAngle: CGFloat(180).degreesToRadians, endAngle: CGFloat(0).degreesToRadians, clockwise: false)
        path.addLine(to: CGPoint(x: self.frame.width, y: 0))
        path.addLine(to: CGPoint(x: self.frame.width, y: self.frame.height))
        path.addLine(to: CGPoint(x: 0, y: self.frame.height))
        path.close()
        return path.cgPath
    }
}

我正在尝试在我的自定义UITabBarController中使用CustomTabBar，但未反映形状。但是，当我使用情节提要板运行时，我可以知道原因了。

class MyTabBarViewController: UITabBarController {

    let customTabBar: CustomTabBar = CustomTabBar()

    override func viewDidLoad() {
        super.viewDidLoad()
        if #available(iOS 13.0, *) {
            self.viewControllers = [UIStoryboard.init(name: "Main", bundle: nil).instantiateViewController(identifier: "FirstViewController"), UIStoryboard.init(name: "Main", bundle: nil).instantiateViewController(identifier: "SecondViewController")]
        } else {
            // Fallback on earlier versions
        }

        // Do any additional setup after loading the view.
    }


    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destination.
        // Pass the selected object to the new view controller.
    }
    */


    override var tabBar: UITabBar {
        return customTabBar
    }

}

我已经尝试在初始化中移动addShape（），但是没有用。关于没有情节提要该怎么办的任何建议。

Answer 1

尝试从MyTabBarViewController调用函数addShape吗？

override func viewWillAppear(_ animated: Bool) {
    self.tabBar.addShape()
}

或

override func viewWillAppear(_ animated: Bool) {
    self.customTabBar.addShape()
}