Swift анимиировать tabcontroller

На основе вашего кода я написал следующий пример. Суть в том, что свойству bezAnimation.toValue нужно присваивать путь, к которому нужно перейти при анимации

import UIKit

class TabBarView: UIView {
    
    private var currentIndex = 0
    private var nextIndex = 0
    
    private var tabsCount: Int {
        items.count
    }
    
    private var tabWidth: CGFloat {
        guard items.count > 0 else {
            return 0
        }
        
        return bounds.width / CGFloat(items.count)
    }
    
    private var tabHeight: CGFloat {
        bounds.height
    }
 
    private var curveLayer: CAShapeLayer!
    
    var items: [String] = []
    var animated = true
    
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setup()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setup()
    }
    
    func setup() {
        let recognizer = UITapGestureRecognizer(target: self, action: #selector(tap(_:)))
        addGestureRecognizer(recognizer)
    }
    
    override func draw(_ rect: CGRect) {
        drawCurve(for: currentIndex)
    }
    
    private func drawCurve(for index: Int) {
        
        let fillColor: UIColor = .white
        let strokeColor: UIColor = .gray
        
        // 1. draw current tab
        
        let currentTabBezierPath = drawPathBorder(for: index)
        currentTabBezierPath.close()
        
        if curveLayer == nil {
            curveLayer = CAShapeLayer()
            curveLayer.fillRule = .evenOdd
            curveLayer.frame = bounds
            curveLayer.fillColor = fillColor.cgColor
            curveLayer.strokeColor = strokeColor.cgColor
            curveLayer.lineWidth = 1
            layer.addSublayer(curveLayer)
        }
        
        curveLayer.path = currentTabBezierPath.cgPath
        
        if currentIndex == nextIndex {
            return
        }
        
        if (self.animated) {
            
            // 2. animate to next tab
            
            let nextTabBezierPath = drawPathBorder(for: nextIndex)
            let bezAnimation = CABasicAnimation(keyPath: "path")
            
            // The next two line preserves the final shape of animation,
            // if you remove it the shape will return to the original shape after the animation finished
            // see https://stackoverflow.com/a/26848581/3004003
            bezAnimation.fillMode = .forwards
            bezAnimation.isRemovedOnCompletion = false
            
            bezAnimation.toValue = nextTabBezierPath.cgPath
            bezAnimation.duration = 3.3
            bezAnimation.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
            curveLayer.add(bezAnimation, forKey: nil)
        }
        
        currentIndex = nextIndex

    }
    
    private func drawPathBorder(for index: Int) -> UIBezierPath {
        let bezPath = UIBezierPath()
        
        let floatIndex = CGFloat(index)
        
        let leftPoint = CGPoint(x: (floatIndex * tabWidth), y: 0)
        let leftPointCurveUp = CGPoint(
            x: ((tabWidth * floatIndex) + tabWidth / 5),
            y: 0)
        // Casting to CGFloat to avoid "The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions"
        let leftPointCurveDown = CGPoint(
            x: ((floatIndex * tabWidth) - tabWidth * CGFloat(0.2)) + tabWidth / CGFloat(4.0),
            y: CGFloat(tabHeight * 0.40))
        
        let middlePoint = CGPoint(
            x: (tabWidth * floatIndex) + tabWidth / 2,
            y: tabHeight * 0.4)
        let middlePointCurveDown = CGPoint(
            x: (((floatIndex * tabWidth) - tabWidth * CGFloat(0.2)) + tabWidth / CGFloat(10.0)) + tabWidth,
            y: tabHeight * 0.40)
        let middlePointCurveUp = CGPoint(
            x: (((tabWidth * floatIndex) + tabWidth) - tabWidth / 5.0),
            y: 0)
        
        let rightPoint = CGPoint(x: (tabWidth * floatIndex) + tabWidth, y: 0)
        
        bezPath.move(to: leftPoint)
        bezPath.addCurve(to: middlePoint, controlPoint1: leftPointCurveUp, controlPoint2: leftPointCurveDown)
        bezPath.addCurve(to: rightPoint, controlPoint1: middlePointCurveDown, controlPoint2: middlePointCurveUp)
        
        let width = UIScreen.main.bounds.width
        bezPath.addLine(to: CGPoint(x: width, y: 0))
        bezPath.addLine(to: CGPoint(x: width, y: 83))
        bezPath.addLine(to: CGPoint(x: 0, y: 83))
        bezPath.addLine(to: CGPoint(x: 0, y: 0))
        bezPath.addLine(to: leftPoint)
        
        return bezPath
    }
    
    @objc func tap(_ recognizer: UITapGestureRecognizer) {
        let location = recognizer.location(in: self)
        nextIndex = tabIndex(with: location)
        setNeedsDisplay()
    }
    
    private func tabIndex(with location:CGPoint) -> Int {
        Int(location.x / tabWidth)
    }
    
}