swift创建带动画的Tababr

class ZZTabBarViewController: UITabBarController {

    //定义默认选中的tabarItem
    var indexFlag = 0
    
    override func viewDidLoad() {
        super.viewDidLoad()
        //设置tabbar背景色
         UITabBar.appearance().barTintColor = UIColor.white
        self.addController()
    }
    //初始化VC
    private func addController()
    {
        self.addchildToShow(FirstViewController(), "首页", "Home", "Home_active")
        self.addchildToShow(SecondViewController(), "分类", "Catalog", "Catalog_active")
        self.addchildToShow(ThreeViewController(), "清单", "list", "list_active")
        self.addchildToShow(FourViewController(), "我的", "User", "User_active")
    }
    //设置vc对应的信息
    private  func addchildToShow(_ childvc: UIViewController, _ titleStr: String, _ image: String, _ selectImage: String) {
        //设置对应vc的文字
        childvc.tabBarItem.title = titleStr
        //设置vc未选中的图片
        childvc.tabBarItem.image = UIImage(named: image)?.withRenderingMode(.alwaysOriginal)
        //设置vc选中时候的图片(给什么图片显示什么图片)
        childvc.tabBarItem.selectedImage = UIImage(named: selectImage)?.withRenderingMode(.alwaysOriginal)
        //选中tabbarItem文字颜色
        UITabBarItem.appearance().setTitleTextAttributes([NSAttributedString.Key.foregroundColor: UIColor.red], for: .selected)
        //头部导航
        let nav = UINavigationController()
        //将视图加入导航控制器的容器里
        nav.addChild(childvc)
        //将导航加入tabbar的控制器容器
        addChild(nav)
        
    }

    //点击item的方法
    
    override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
        if let index = tabBar.items?.firstIndex(of: item)
        {
            if indexFlag != index {
                self.animationWithIndex(index: index)
            }
        }
    }
    //实现缩放动画
    private func animationWithIndex(index: Int){
         var arrViews = [UIView]()
        for tabbarButton in tabBar.subviews {
            //遍历tabbar上面的bUITabBarButton
            if tabbarButton.isKind(of: NSClassFromString("UITabBarButton")!) {
                arrViews.append(tabbarButton)
            }
        }
        let animation = CABasicAnimation(keyPath: "transform.scale")
        //动画执行的时间函数
        animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeInEaseOut)
        //动画执行时间
        animation.duration = 0.3
        //动画重复次数
        animation.repeatCount = 1
        //动画是否恢复原始状态
        animation.autoreverses = true
        //初始key
        animation.fromValue = NSNumber(value: 0.8)
        //结束key
        animation.toValue = NSNumber(value: 1.1)
        //把动画加载到点点击的那个tabbarItem上
        arrViews[index].layer.add(animation, forKey: nil)
        //赋值记录点击的tababrItem
        indexFlag = index
        
    }
}