iOS自定义UITabBar仿今日头条效果

override func viewDidLoad() {
 super.viewDidLoad()
 // 替换 tabbar
 let _tabBar = TabBar()
 // 监听按钮点击事件
 _tabBar.handleBtnReleaseClick(self, action: #selector(btnReleaseClick))
 setValue(_tabBar, forKey: "tabBar")
}

// MARK: 删除占位“按钮”，添加自定义按钮
override func layoutSubviews() {
 super.layoutSubviews()
 btnRelease.backgroundColor = UIColor.white
 // 过滤掉 _UIBarBackground 类型的对象，只保留 UITabBarButton 类型的对象
 let tabbarButtonList = iews.filter{NSStringFromClass(type(of: $0)) == abBarButton"}
 // 取出需要删除的“按钮”（经测试，知道中间那个加号按钮的下标是2）
 let tmpView = tabbarButtonList[safe: 2]
 // 把默认生成的从父容器中移除
 tmpView?.removeFromSuperview()
 let x = (InnerConst.ScreenW - btnRelease.w) * 0.5
 let y = InnerConst.ButtonOffsetY
 btnRelease.origin = CGPoint(x: x, y: y)
 addSubview(btnRelease)
}

// MARK: 处理默认情况下，按钮超出 TabBar 以外区域不能点击问题
override func hitTest(_ point: CGPoint, with event: UIEvent?) -View? {
 if isHidden == false {
  let newPoint = convert(point, to: btnRelease)
  if btnRelease.point(inside: newPoint, with: event) {
   return btnRelease
  }
  return super.hitTest(point, with: event)
 }
 return super.hitTest(point, with: event)
}

func handleBtnReleaseClick(_ target: AnyObject?, action: Selector) {
 btnRelease.addTarget(target, action: action, for: .touchUpInside)
}